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Louwrentius

Louwrentius
My 71 TiB ZFS NAS after 10 years and zero drive failures My 4U 71 TiB ZFS NAS built with twenty-four 4 TB drives is over 10 years old and still going...
4 months ago
9
4 months ago
My 4U 71 TiB ZFS NAS built with twenty-four 4 TB drives is over 10 years old and still going strong. Although now on its second motherboard and power supply, the system has yet to experience a single drive failure (knock on wood). Zero drive failures in ten years, how is that...
Louwrentius
The Raspberry Pi 5 is no match for a tini-mini-micro PC I've always been fond of the idea of the Raspberry Pi. An energy efficient, small, cheap but capable...
7 months ago
7
7 months ago
I've always been fond of the idea of the Raspberry Pi. An energy efficient, small, cheap but capable computer. An ideal home server. Until the Pi 4, the Pi was not that capable, and only with the relatively recent Pi 5 (fall 2023) do I feel the Pi is OK performance wise, although...
Louwrentius
AI is critically important but not for you Before Chat-GPT caused a sensation, big tech companies like Facebook and Apple were betting their...
8 months ago
6
8 months ago
Before Chat-GPT caused a sensation, big tech companies like Facebook and Apple were betting their future growth on virtual reality. But I'm convinced that virtual reality will never be a mainstream thing. If you ever used VR you know why: A heavy thing on your head that messes up...
Louwrentius
How to run victron veconfigure on a mac Introduction Victron Multiplus-II inverter/charges are configured with the veconfigure1 tool....
11 months ago
12
11 months ago
Introduction Victron Multiplus-II inverter/charges are configured with the veconfigure1 tool. Unforntunately this is a Windows-only tool, but there is still a way for Apple users to run this tool without any problems. Tip: if you've never worked with the Terminal app on MacOS, it...
Louwrentius
Tunneling Elixir cluster network traffic over Wireguard Introduction The other day I was supporting a customer with an Elixir-based platform that would make...
a year ago
7
a year ago
Introduction The other day I was supporting a customer with an Elixir-based platform that would make use of Elixir libcluster, so messages on one host can be passed to other hosts. This can - for example - enable live updates for all users, even if they are not communicating with...
Louwrentius
IKEA $50 VINDSTYRKA vs. $290 Dylos air quality monitor This is a brief article in which I compare the IKEA VINDSTYRKA $50 air quality monitor (PM2.5) with...
a year ago
8
a year ago
This is a brief article in which I compare the IKEA VINDSTYRKA $50 air quality monitor (PM2.5) with a $290 air quality monitor made by Dylos to see if it's any good. Context If you care about indoor air quality, you may already own a CO2 to determine if it's time to ventilate...
Louwrentius
My solar-powered blog is now on Lithium Iron Phosphate In my last blog post I discussed how a small solar project - to power this blog on a Raspberry Pi -...
a year ago
7
a year ago
In my last blog post I discussed how a small solar project - to power this blog on a Raspberry Pi - escalated into a full-blown off-grid solar setup, large enough to power the computer I use at the moment to write this update1. In this update, I want to discuss my battery...
Louwrentius
I made my blog solar-powered, then things escalated In 2020 I wondered if I could run my blog on solar power, being inspired by Low-tech Magazine, doing...
a year ago
8
a year ago
In 2020 I wondered if I could run my blog on solar power, being inspired by Low-tech Magazine, doing the same thing (but better)1. The answer was 'yes', but only through spring and summer. I live in an apartment complex in The Netherlands and my balcony is facing west. This...
Louwrentius
Benchmarking cheap SSDs for fun, no profit (be warned) The price of Solid-state drives (SSDs) has dropped significantly over the last few years. It's now...
a year ago
8
a year ago
The price of Solid-state drives (SSDs) has dropped significantly over the last few years. It's now possible to buy a 1TB solid-state drive for less than €60. However, at such low price points, there is a catch. Although cheap SSDs do perform fine regarding reads, sustained write...
Louwrentius
How to setup a local or private Ubuntu Mirror Preface In this article I provide instructions on how to setup a local Ubuntu mirror using...
over a year ago
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over a year ago
Preface In this article I provide instructions on how to setup a local Ubuntu mirror using debmirror. To set expectations: the mirror will work as intended and distribute packages and updates, but a do-release upgrade from one major version of Ubuntu to the next won't...
Louwrentius
I resurrected my Dutch movie review site from 2003 Introduction Between 2003 and 2006, I ran a Dutch movie review site called moevie.nl.1 I built the...
over a year ago
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over a year ago
Introduction Between 2003 and 2006, I ran a Dutch movie review site called moevie.nl.1 I built the site and wrote the reviews. It never made any money. It cost me money to host, and it cost me a lot of time writing reviews, but I remember enjoying writing reviews about films I...
Louwrentius
An ode to the 10,000 RPM Western Digital (Veloci)Raptor Introduction Back in 2004, I visited a now bankrupt Dutch computer store called MyCom1, located at...
over a year ago
5
over a year ago
Introduction Back in 2004, I visited a now bankrupt Dutch computer store called MyCom1, located at the Kinkerstraat in Amsterdam. I was there to buy a Western Digital Raptor model WD740, with 74 GB of capacity, running at 10,000 RPM. When I bought this drive, we were still in...
Louwrentius
Raspberry Pi as a router using a single network interface Introduction Disclaimer: this article is intended for consumers and hobbyists. If you want to run...
over a year ago
10
over a year ago
Introduction Disclaimer: this article is intended for consumers and hobbyists. If you want to run your own router at home, the Raspberry Pi 4 Model B1 can be an excelent hardware choice: it's fairly cheap it's fast enough it can saturate it's gigabit network port it is...
Louwrentius
A practical understanding of lead acid batteries Introduction The goal of this article is to give you a practical understanding Lead Acid batteries....
over a year ago
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over a year ago
Introduction The goal of this article is to give you a practical understanding Lead Acid batteries. We won't address the underlying chemistry, we'll treat them as a black-box and we will discover their characteristics and how to keep them healthy. Disclaimer I'm an amateur. I...
Louwrentius
ZFS RAIDZ expansion is awesome but has a small caveat Introduction Update April 2023: It has been fairly quiet since the announcement of this feature. The...
over a year ago
5
over a year ago
Introduction Update April 2023: It has been fairly quiet since the announcement of this feature. The Github PR about this feature is rather stale and people are wondering what the status is and what the plans are. Meanwhile, FreeBSD has announced In February 2023 that they...
Louwrentius
Recycle your old laptop display and turn it into a monitor During a cleaning spree I decided that it was time to recycle two old laptops that were just...
over a year ago
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over a year ago
During a cleaning spree I decided that it was time to recycle two old laptops that were just collecting dust on a shelf for many years. Although I didn't have any purpose for them anymore, I realised that the displays were still perfectly fine. This is the display of my old 13"...
Louwrentius
Understanding the Ubuntu 20.04 LTS Server Autoinstaller Introduction Ubuntu Server version 18.04 LTS uses the debian-installer (d-i) for the installation...
over a year ago
8
over a year ago
Introduction Ubuntu Server version 18.04 LTS uses the debian-installer (d-i) for the installation process. This includes support for 'preseeding' to create unattended (automated) installations of ubuntu. the debian installer With the introduction of Ubuntu Server 20.04 'Focal...
Louwrentius
A 12.48 inch (1304x984) three-color e-paper display by Waveshare Introduction Update September 2023: A small horizontal and large vertical row of pixels died. Demo...
over a year ago
8
over a year ago
Introduction Update September 2023: A small horizontal and large vertical row of pixels died. Demo of defective display here. I'm running a solar-powered blog and I wanted to add a low-power display to show the daily solar 'harvest'1 and maybe some additional information. So I...
Louwrentius
Most Technical debt is just bullshit Introduction I made an offhand remark about technical debt to a friend and he interrupted me,...
over a year ago
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over a year ago
Introduction I made an offhand remark about technical debt to a friend and he interrupted me, saying: "technical debt is just bullshit". In his experience, people talking about technical debt were mostly trying to: cover up bad code cover up unfinished work source1 Calling...
Louwrentius
This blog is now running on solar power Introduction This blog is now running on solar power. I've put a solar panel on my balcony, which...
over a year ago
9
over a year ago
Introduction This blog is now running on solar power. I've put a solar panel on my balcony, which is connected to a solar charge controller. This device charges an old worn-out car battery and provides power to a Raspberry Pi ~~3b+~~ 4B, which in turn powers this (static)...
Louwrentius
Don't be afraid of RAID Introduction I sense this sentiment on the internet that RAID is dangerous, that the likelihood of...
over a year ago
9
over a year ago
Introduction I sense this sentiment on the internet that RAID is dangerous, that the likelihood of your RAID array failing during a rebuild is almost a certainty, because hard drives have become so large. I think nothing is further from the truth and I would like to dispel this...
Louwrentius
What home NAS builders should understand about silent data corruption Introduction When it comes to dealing with storage in a DIY NAS context, two important topics come...
over a year ago
8
over a year ago
Introduction When it comes to dealing with storage in a DIY NAS context, two important topics come up: Unrecoverable read errors (UREs) or what old people like me call 'bad sectors' Silent data corruption (data corruption unnoticed by the storage layers) I get a strong impression...
Louwrentius
Scrub your NAS hard drives regularly if you care about your data Introduction Lots of people run a NAS at home. Maybe it's a COTS device from one of the well-known...
over a year ago
8
over a year ago
Introduction Lots of people run a NAS at home. Maybe it's a COTS device from one of the well-known vendors1, or it's a custom build solution (DIY2) based on hardware you bought and assembled yourself. Buying or building a NAS is one thing, but operating it in a way that assures...
Louwrentius
Benchmarking storage with Fio and generating charts of the results Introduction Fio is a widely-used tool for performing storage benchmarks. Fio offers a lot of...
over a year ago
6
over a year ago
Introduction Fio is a widely-used tool for performing storage benchmarks. Fio offers a lot of options to create a storage benchmark that would best reflect your needs. Fio allows you to assess if your storage solution is up to its task and how much headroom it has. Fio outputs...
Louwrentius
My home network setup based on managed switches and VLANs My home networking setup I live in a two story apartment, with on the top floor my utilities closet...
over a year ago
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over a year ago
My home networking setup I live in a two story apartment, with on the top floor my utilities closet and my living room. The bottom floor contains a bedroom with all my servers and networking gear. So this is my setup (click for a bigger version): I like to run my own router but...
Louwrentius
The impact of the MDADM bitmap on RAID performance Introduction I'm aware that most people with intensive storage workloads won't run those workloads...
over a year ago
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over a year ago
Introduction I'm aware that most people with intensive storage workloads won't run those workloads on hard drives anymore, that ship has sailed a long time ago. SSDs have taken their place (or 'the cloud'). For those few left who do use hard drives in Linux software RAID setups...
Louwrentius
Cryptocurrencies are detrimental to society Want to listen to this article? audio element. Introduction How would you explain the inner...
over a year ago
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over a year ago
Want to listen to this article? audio element. Introduction How would you explain the inner workings of bitcoin to a person in simple, understandable terms? source This explanation seems perfect to me because it illustrates some seriously problematic aspects of...
Louwrentius
Understanding Storage Performance - IOPS and Latency Introduction The goal of this blogpost is to help you better understand storage performance. I want...
over a year ago
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over a year ago
Introduction The goal of this blogpost is to help you better understand storage performance. I want to discuss some fundamentals that are true regardless of your particular needs. This will help you better reason about storage and may provide a scaffolding for further learning....
Louwrentius
Difference of behavior in SATA Solid State Drives Introduction Update: I've noticed some strange behavior of SSDs when benchmarking them with FIO....
over a year ago
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over a year ago
Introduction Update: I've noticed some strange behavior of SSDs when benchmarking them with FIO. After further investigation and additional testing, I've found the reason for the strange patterns in the graphs. The 'strange' test results are due to the fact that they were...
Louwrentius
Benchmarking a 1.44 MB floppy drive I've used fio - a storage benchmarking tool - to benchmark a 1.44 MB floppy drive to gauge its...
over a year ago
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over a year ago
I've used fio - a storage benchmarking tool - to benchmark a 1.44 MB floppy drive to gauge its random I/O performance. I have no real reason for doing this. I just thought it was funny. I've run a benchmark against the floppy drives for different queue depths. The results are...
Louwrentius
Fio-plot: creating nice charts from FIO storage benchmark data New release of fio-plot I've rewritten fio-plot, a tool that turns FIO benchmark data into nice...
over a year ago
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over a year ago
New release of fio-plot I've rewritten fio-plot, a tool that turns FIO benchmark data into nice charts. It allows you to create four types of graphs which will be discussed below. The github project page explains how to run this tool. Fio-plot also includes a benchmark script...
Louwrentius
My home lab server with 20 cores / 40 threads and 128 GB memory Update fall 2024 I have decided to decomission this machine and it is no longer in use. As of this...
over a year ago
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over a year ago
Update fall 2024 I have decided to decomission this machine and it is no longer in use. As of this moment, it's replaced by a cluster of four 1L PCs which use about a third of the idle power usage and boot within 20 seconds. The single-core performance of these low-power 1L PCs...
Louwrentius
My Ceph test cluster based on Raspberry Pi's and HP MicroServers Introduction To learn more about Ceph, I've build myself a Ceph Cluster based on actual hardware. In...
over a year ago
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over a year ago
Introduction To learn more about Ceph, I've build myself a Ceph Cluster based on actual hardware. In this blogpost I'll discus the cluster in more detail and I've also included (fio) benchmark results. This is my test Ceph cluster: The cluster consists of the following...
Louwrentius
Compiling Ceph on the Raspberry Pi 3B+ (armhf) using Clang/LLVM UPDATE 2019 / 2020 There are official ARM64 binaries of Ceph that you can run on a 64-bit version of...
over a year ago
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over a year ago
UPDATE 2019 / 2020 There are official ARM64 binaries of Ceph that you can run on a 64-bit version of Ubuntu 18.04. Important: I consider this page obsolete. I will keep it up for transparency's sake Introduction In this blog post I'll show you how to compile Ceph Luminous for...
Louwrentius
Understanding Ceph: open-source scalable storage Introduction In this blog post I will try to explain why I believe Ceph is such an interesting...
over a year ago
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over a year ago
Introduction In this blog post I will try to explain why I believe Ceph is such an interesting storage solution. After you finished reading this blog post you should have a good high-level overview of Ceph. I've written this blog post purely because I'm a storage enthusiast and I...
Louwrentius
Setup a VPN on your iPhone with OpenVPN and Linux ⚠️ 🚨 Update 2024 🚨⚠️ I'm not using OpenVPN anymore for my VPN needs and this article is considered...
over a year ago
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over a year ago
⚠️ 🚨 Update 2024 🚨⚠️ I'm not using OpenVPN anymore for my VPN needs and this article is considered unmaintained. It's stronly recommended not to use this tutorial and find up-to-date documentation. I also have no plans to update this blogpost in the future. [Update 2018] This...
Louwrentius
HP Proliant Microserver Gen10 as router or NAS Introduction In the summer of 2017, HP released the Proliant Microserver Gen10. This machine...
over a year ago
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over a year ago
Introduction In the summer of 2017, HP released the Proliant Microserver Gen10. This machine replaces the older Gen8 model. For hobbyists, the Microserver always has been an interesting device for a custom home NAS build or as a router. Let's find out if this is still the case....
Louwrentius
Using InfiniBand for cheap and fast point-to-point Networking InfiniBand networking is quite awesome. It's mainly used for two reasons: low latency high...
over a year ago
9
over a year ago
InfiniBand networking is quite awesome. It's mainly used for two reasons: low latency high bandwidth As a home user, I'm mainly interested in setting up a high bandwidth link between two servers. I was using quad-port network cards with Linux Bonding, but this solution has some...
Louwrentius
Tracking down a faulty Storage Array Controller with ZFS One day, I lost two virtual machines on our DR environment after a storage vMotion. Further...
over a year ago
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over a year ago
One day, I lost two virtual machines on our DR environment after a storage vMotion. Further investigation uncovered that any storage vMotion of a virtual machine residing on our DR storage array would corrupt the virtual machine's disks. I could easily restore the affected...
Louwrentius
RAID 5 is perfectly fine for home usage RAID 5 gets a lot of flak these days. You either run RAID 1, RAID 10 or you use RAID 6, but if you...
over a year ago
6
over a year ago
RAID 5 gets a lot of flak these days. You either run RAID 1, RAID 10 or you use RAID 6, but if you run RAID 5 you're told that you are a crazy person. Using RAID 5 is portrayed as an unreasonable risk to the availability of your data. It is suggested that it is likely that you...
Louwrentius
ZFS: resilver performance of various RAID schemas When building your own DIY home NAS, it is important that you simulate and test drive failures...
over a year ago
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over a year ago
When building your own DIY home NAS, it is important that you simulate and test drive failures before you put your important data on it. It makes sense to know what to do in case a drive needs to be replaced. I also recommend putting a substantial amount of data on your NAS and...
Louwrentius
The 'hidden' cost of using ZFS for your home NAS Introduction Update December 2023: In June, it was announced that iXsystems would sponsor...
over a year ago
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over a year ago
Introduction Update December 2023: In June, it was announced that iXsystems would sponsor implementing the VDEV expansion feature. A new pr has been created for this effort. The feature was merged into the code base, but may not be available to the general public before the end...
Louwrentius
ZFS performance on HP Proliant Microserver Gen8 G1610T I think the HP Proliant Microserver Gen8 is a very interesting little box if you want to build your...
over a year ago
11
over a year ago
I think the HP Proliant Microserver Gen8 is a very interesting little box if you want to build your own ZFS-based NAS. The benchmarks I've performed seem to confirm this. The Microserver Gen8 has nice features such as: iLO (KVM over IP with dedicated network interface) support...
Louwrentius
The sorry state of CoW file systems I'd like to argue that both ZFS and BTRFS both are incomplete file systems with their own drawbacks...
over a year ago
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over a year ago
I'd like to argue that both ZFS and BTRFS both are incomplete file systems with their own drawbacks and that it may still be a long way off before we have something truly great. Both ZFS and BTRFS are two heroic feats of engineering, created by people who are probably ten times...
Louwrentius
Configuring SCST iSCSI target on Debian Linux (Wheezy) My goal is to export ZFS zvol volumes through iSCSI to other machines. The platform I'm using is...
over a year ago
4
over a year ago
My goal is to export ZFS zvol volumes through iSCSI to other machines. The platform I'm using is Debian Wheezy. There are three iSCSI target solutions available for Linux: LIO IET SCST I've briefly played with LIO but the targetcli tool is interactive only. If you want to...
Louwrentius
Why I Do Use ZFS as a File System for My NAS On February 2011, I posted an article about my motivations why I did not use ZFS as a file system...
over a year ago
8
over a year ago
On February 2011, I posted an article about my motivations why I did not use ZFS as a file system for my 18 TB NAS. You have to understand that at the time, I believe the arguments in the article were relevant, but much has changed since then, and I do believe this article is...
Louwrentius
FreeBSD 10.1 unattended install over PXE & HTTP (no NFS) To gain some more experience with FreeBSD, I decided to make a PXE-based unattended installation of...
over a year ago
8
over a year ago
To gain some more experience with FreeBSD, I decided to make a PXE-based unattended installation of FreeBSD 10.1. My goal is to set something up similar to Debian/Ubuntu + preseeding or Redhat/CentOS + kickstart. Getting a PXE-based unattended installation of FreeBSD 10.1 was...
Louwrentius
Creating configuration backups of HP procurve switches I've created a tool called procurve-watch. It creates a backup of the running switch configuration...
over a year ago
6
over a year ago
I've created a tool called procurve-watch. It creates a backup of the running switch configuration through secure shell (using scp). It also diffs backed up configurations against older versions, in order to keep track of changes. If you run the script from cron every hour or...
Louwrentius
Configuring, attacking and securing VRRP on Linux The VRRP or Virtual Router Redundancy Protocol helps you create a reliable network by using multiple...
over a year ago
12
over a year ago
The VRRP or Virtual Router Redundancy Protocol helps you create a reliable network by using multiple routers in an active/passive configuration. If the primary router fails, the backup router takes over almost seamlessly. This is how VRRP works: Clients connect to a virtual...
Louwrentius
Systemd Forward Secure Sealing of system logs makes little sense Systemd is a more modern replacement of sysvinit and its in the process of being integrated into...
over a year ago
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over a year ago
Systemd is a more modern replacement of sysvinit and its in the process of being integrated into most mainstream Linux distributions. I'm a bit troubled by one of it's features. I'd like to discuss the Forward Secure Sealing (FSS) feature for log files that is part of systemd....
Louwrentius
Getting the Sitecom AC600 Wi-Fi adapter running on Linux TL;DR Yes it works with some modifications of the driver source. A USB Wi-Fi adapter I used with a...
over a year ago
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over a year ago
TL;DR Yes it works with some modifications of the driver source. A USB Wi-Fi adapter I used with a Raspberry Pi broke as I dropped it on the floor, so I had to replace it. I just went to a local shop and bought the Sitecom AC600 adapter as that's what they had available (with...
Louwrentius
The ZFS Event Daemon on Linux If something goes wrong with my zpool, I'd like to be notified by email. On Linux using MDADM, the...
over a year ago
8
over a year ago
If something goes wrong with my zpool, I'd like to be notified by email. On Linux using MDADM, the MDADM daemon took care of that. With the release of ZoL 0.6.3, a brand new 'ZFS Event Daemon' or ZED has been introduced. I could not find much information about it, so consider...
Louwrentius
Installation of ZFS on Linux hangs on Debian Wheezy This article is no longer relevant. After a fresh net-install of Debian Wheezy, I was unable to...
over a year ago
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over a year ago
This article is no longer relevant. After a fresh net-install of Debian Wheezy, I was unable to compile the ZFS for Linux kernel module. I've installed apt-get install build-essential but that wasn't enough. The apt-get install debian-zfs command would just hang. I noticed a...
Louwrentius
Please use ZFS with ECC Memory In this blogpost I argue why it's strongly recommended to use ZFS with ECC memory when building a...
over a year ago
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over a year ago
In this blogpost I argue why it's strongly recommended to use ZFS with ECC memory when building a NAS. I would argue that if you do not use ECC memory, it's reasonable to also forgo on ZFS altogether and use any (legacy) file system that suits your needs. Why ZFS? Many people...
Louwrentius
71 TiB DIY NAS based on ZFS on Linux This is my new 71 TiB DIY NAS. This server is the successor to my six year old, twenty drive 18 TB...
over a year ago
5
over a year ago
This is my new 71 TiB DIY NAS. This server is the successor to my six year old, twenty drive 18 TB NAS (17 TiB). With a storage capacity four times higher than the original and an incredible read (2.5 GB/s)/write (1.9 GB/s) performance, it's a worthy successor. Purpose The...
Louwrentius
ZFS: Performance and capacity impact of ashift=9 on 4K sector drives Update 2014-8-23: I was testing with ashift for my new NAS. The ashift=9 write performance...
over a year ago
5
over a year ago
Update 2014-8-23: I was testing with ashift for my new NAS. The ashift=9 write performance deteriorated from 1.1 GB/s to 830 MB/s with just 16 TB of data on the pool. Also I noticed that resilvering was very slow. This is why I decided to abandon my 24 drive RAIDZ3...
Louwrentius
Achieving 2.3 GB/s with 16 x 4 TB drives I'm in the process of building a new storage server to replace my 18 TB NAS. The server is almost...
over a year ago
5
over a year ago
I'm in the process of building a new storage server to replace my 18 TB NAS. The server is almost finished, it's now down to adding disk drives. I'm using the HGST 4 TB 7200 RPM drive for this build (SKU 0S03356) (review). I have not bought all drives at once, but slowly adding...
Louwrentius
Affordable server with server-grade hardware part II If you want to build a home server, it may be advised to actually use server-grade components. I...
over a year ago
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over a year ago
If you want to build a home server, it may be advised to actually use server-grade components. I documented the reasons for choosing server-grade hardware already in an earlier post on this topic. It is recommended to read the old post first. In this new post, I only show new...
Louwrentius
How to resolve extreme memory usage on Windows 2008 R2-based file servers I'm responsible for a file server with about 5 terrabytes of data. The file server is based on...
over a year ago
5
over a year ago
I'm responsible for a file server with about 5 terrabytes of data. The file server is based on Windows 2008 R2. I've noticed extreme memory usage on the server. After a reboot, it slowly builds up until almost all RAM memory is consumed. So I googled around and found this post...
Louwrentius
My experiences with DFS replication on Windows 2008 R2 If you are considering implementing DFS replication, consider using Windows 2012 R2 because DFS...
over a year ago
10
over a year ago
If you are considering implementing DFS replication, consider using Windows 2012 R2 because DFS replication has been massively improved. It supports larger data sets and performance has dramatically been improved over Windows 2008 R2. I've implemented DFS replication to keep two...
Louwrentius
How traffic shaping can dramatically improve internet responsiveness At work, access to the internet is provided by a 10 Mbit down / 1 Mbit up ADSL-connection. As we are...
over a year ago
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over a year ago
At work, access to the internet is provided by a 10 Mbit down / 1 Mbit up ADSL-connection. As we are a mid-size company, bandwidth is clearly a severe constraint. But it was not our biggest problem. Even simple web-browsing was very slow. As I was setting up a monitoring...
Louwrentius
Monitoring HP MSA P2000 G3 I/O latency with Nagios At work we have a couple of HP MSA P2000 G3 SANs. These are entry-level SANs that still seem to have...
over a year ago
5
over a year ago
At work we have a couple of HP MSA P2000 G3 SANs. These are entry-level SANs that still seem to have almost all features you might want from a SAN, except for official SSD-support. It seems that the new MSA 2040 adds support for SSDs and also provides 4 GB cache per controller...
Louwrentius
Creating a basic ZFS file system on Linux Here are some notes on creating a basic ZFS file system on Linux, using ZFS on Linux. I'm...
over a year ago
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over a year ago
Here are some notes on creating a basic ZFS file system on Linux, using ZFS on Linux. I'm documenting the scenario where I just want to create a file system that can tollerate at least a single drive failure and can be shared over NFS. Identify the drives you want to use for the...
Louwrentius
Why you should not use IPsec for VPN connectivity IPsec is a well-known and widely-used VPN solution. It seems that it's not widely known that Niels...
over a year ago
7
over a year ago
IPsec is a well-known and widely-used VPN solution. It seems that it's not widely known that Niels Ferguson and Bruce Schneier performed a detailed security analysis of IPsec and that the results were not very positive. We strongly discourage the use of IPsec in its current form...
Louwrentius
Achieving 450 MB/s network file transfers using Linux Bonding Linux Bonding In this article I'd like to show the results of using regular 1 Gigabit network...
over a year ago
13
over a year ago
Linux Bonding In this article I'd like to show the results of using regular 1 Gigabit network connections to achieve 450 MB/s file transfers over NFS. I'm again using Linux interface bonding for this purpose. Linux interface bonding can be used to create a virtual network...
Louwrentius
Things you should consider when building a ZFS NAS ZFS is a modern file system designed by Sun Microsystems, targeted at enterprise environments. Many...
over a year ago
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over a year ago
ZFS is a modern file system designed by Sun Microsystems, targeted at enterprise environments. Many features of ZFS also appeal to home NAS builders and with good reason. But not all features are relevant or necessary for home use. I believe that most home users building their...
Louwrentius
ZFS on Linux: monitor cache hit ratio I'm performing some FIO random read 4k I/O benchmarks on a ZFS file system. So since I didn't trust...
over a year ago
4
over a year ago
I'm performing some FIO random read 4k I/O benchmarks on a ZFS file system. So since I didn't trust the numbers I got, I wanted to know how many of the IOPs I got were due to cache hits rather than disk hits. This is why I wrote a small shell script called archhitratio. Sample...
Louwrentius
An affordable server platform based on server-grade hardware Updated post (June 2014) found HERE There are some reasons why you should consider buying true...
over a year ago
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over a year ago
Updated post (June 2014) found HERE There are some reasons why you should consider buying true server-grade harware when building a server, wether it's for home or business use. This is why I want to introduce you to the Supermicro X9SCM-F motherboard. This motherboard costs...
Louwrentius
Eztables: simple yet powerful firewall configuration for Linux I've created and released Eztables on Github. Anyone who ever has a need to setup a firewall on...
over a year ago
7
over a year ago
I've created and released Eztables on Github. Anyone who ever has a need to setup a firewall on Linux may be interested in this project. It doesn't matter if you need to protect a laptop, server or want to setup a network firewall. Eztables supports it all. If you're not afraid...
Louwrentius
Script that shows smart values of all disks' Please use this tool on github instead of this ancient script. So you have a Linux system with a lot...
over a year ago
7
over a year ago
Please use this tool on github instead of this ancient script. So you have a Linux system with a lot of hard drives. If you want to quickly check on some key SMART values to determine the health of individual disks, you might be interested in this script. I wrote a small Python...
Louwrentius
Script that shows relevant disk information I wrote a small Python script called 'showdisks' that displays relevant information about any...
over a year ago
10
over a year ago
I wrote a small Python script called 'showdisks' that displays relevant information about any physical storage devices supported by hdparm. Information such as model and capacity are shown, but also controller and device path. This script only requires python and hdparm. I hope...
Louwrentius
Finding a good blu-ray player for Mac OS X I find playing a Blu-ray movie on my Mac cumbersome. I've been using Plex, XBMC and VLC but these...
over a year ago
8
over a year ago
I find playing a Blu-ray movie on my Mac cumbersome. I've been using Plex, XBMC and VLC but these free open-source products are all a usability nightmare. To play a Blu-ray movie, you have to perform these steps: right-click on the BDMV file choose 'show packet contents' go to...
Louwrentius
Linux: script that creates table of network interface properties My server has 5 network interfaces and I wanted a quick overview of some properties. There may be an...
over a year ago
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over a year ago
My server has 5 network interfaces and I wanted a quick overview of some properties. There may be an existing linux command for this but I couldn't find it so I quickly wrote my own script (download). This is the output: The only requirement for this script is that you have...
Louwrentius
How to compile HAProxy from source and setup a basic configuration To learn more about HAProxy I decided to compile it from source and use it to load-balance traffic...
over a year ago
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over a year ago
To learn more about HAProxy I decided to compile it from source and use it to load-balance traffic to louwrentius.com across two different web servers. I run HAProxy on a VPS based on Ubuntu 12.04 LTS. Let's dive right in. First, we need to download the source. Don't copy/pased...
Louwrentius
Redhat explains why chroot is not a security feature I came across this Redhat security blog post that explains why the chroot command has it's uses, but...
over a year ago
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over a year ago
I came across this Redhat security blog post that explains why the chroot command has it's uses, but it isn't magic security pixie dust. Running an application from within a chrooted jail or just on a well-configured system would result in the same level of security. Josh...
Louwrentius
overview of open-source load balancers I was looking at open-source load balancing software and it seems that there isn't a nice overview...
over a year ago
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over a year ago
I was looking at open-source load balancing software and it seems that there isn't a nice overview except from this website, although many of the listed projects seem dead. I've made a selection of products that seem to be relevant. The biggest problem with open-source software...
Louwrentius
I switched my blog from Blogofile to Pelican This blog is a static website, which makes it fast, simple and secure. It was generated by Blogofile...
over a year ago
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over a year ago
This blog is a static website, which makes it fast, simple and secure. It was generated by Blogofile but I switched to Pelican. Blogofile has seen almost no updates over the years and I consider the project dead. Realising that blogofile is dead, I decided to look around for...
Louwrentius
Using iSCSI with time machine and Super Duper In the past, as a Mac user, I've used separate external drives for Time Machine backups and Super...
over a year ago
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over a year ago
In the past, as a Mac user, I've used separate external drives for Time Machine backups and Super Duper clones but I'm not happy with that. External hard drives make noise and create clutter. I'd like to move away all my storage from my living room (or home office) and put it in...
Louwrentius
Don't use cloud services if you care about secrecy of your data When you use cloud services, you are storing your data on other people's hard drives. The moment you...
over a year ago
5
over a year ago
When you use cloud services, you are storing your data on other people's hard drives. The moment you put your data within a cloud service, that data is no longer under your control. You don't know who will access that data. Secrecy is lost. Instead of using services like Gmail...
Louwrentius
Why I believe the new Mac Pro won't be a great machine for gaming In Accidental Tech Podcast episode 18 (love the show), I learned that John Siracusa was thinking...
over a year ago
5
over a year ago
In Accidental Tech Podcast episode 18 (love the show), I learned that John Siracusa was thinking about buying a new Mac Pro for gaming. I believe that gaming on the new Mac Pro will be a mediocre experience. Driver support: as John mentioned himself, the video cards are...
Louwrentius
Improving iSCSI Native Multi Pathing Round Robin performance 10 Gb ethernet is still quite expensive. You not only need to buy appropriate NICS, but you must...
over a year ago
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over a year ago
10 Gb ethernet is still quite expensive. You not only need to buy appropriate NICS, but you must also upgrade your network hardware as well. You may even need to replace existing fiber optic cabling if it's not rated for 10 Gbit. So I decided to still just go for plain old 1...
Louwrentius
Creating storage benchmark charts with FIO and GNUplot Edit 2019: I've made a new tool called 'fio-plot'to create various graphs. I use FIO to perform...
over a year ago
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over a year ago
Edit 2019: I've made a new tool called 'fio-plot'to create various graphs. I use FIO to perform storage IO performance benchmarks. FIO does provide a script called "fio_generate_plots" which generates PNG or JPG based charts based on the data generated by FIO. The charts are...
Louwrentius
Linode hacked: the dark side of cloud hosting Linode has released an update about the security incident first reported on April 12, 2013. The...
over a year ago
5
over a year ago
Linode has released an update about the security incident first reported on April 12, 2013. The Linode Manager is the environment where you control your virtual private servers and where you pay for services. This is the environment that got compromised. Linode uses Adobe's...
Louwrentius
Linode hacked: thoughts about cloud security I bought a Linode VPS for private usage just after the report that Linode had reset all passwords of...
over a year ago
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over a year ago
I bought a Linode VPS for private usage just after the report that Linode had reset all passwords of existing users regarding the Linode management console. Resetting passwords is not something you do when under a simple attack such as a DDOS attack. Such a measure is only taken...
Louwrentius
Storage and I/O: reads vs. writes There is a fundamental difference between a read operation and a write operation. Storage can lie...
over a year ago
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over a year ago
There is a fundamental difference between a read operation and a write operation. Storage can lie about completing a write operation, but it can never lie about completing a read operation. Therefore read and writes have different characteristics. This is what I've learned. About...
Louwrentius
Benchmark results of Random I/O performance of different RAID levels Introduction I have performed some benchmarks to determine how different RAID levels perform when...
over a year ago
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over a year ago
Introduction I have performed some benchmarks to determine how different RAID levels perform when handling a 100% random workload of 4K requests. This is a worst-case scenario for almost every storage subsystem. Normal day-to-day workloads may not be that harsh in a real-life...
Louwrentius
Statistics showing relevance of caching proxy In this day and age of dynamic web content, how relevant can a caching proxy server be? I believe...
over a year ago
8
over a year ago
In this day and age of dynamic web content, how relevant can a caching proxy server be? I believe that the answer could be: quite! I have installed a caching proxy server based on Squid, which is now used within my company. It also does content scanning using squidclamav and...
Louwrentius
Understanding IOPS, latency and storage performance Update 2020: I've written another blogpost about this topic, including some benchmark examples. When...
over a year ago
11
over a year ago
Update 2020: I've written another blogpost about this topic, including some benchmark examples. When most people think about storage performance, they think about throughput. But throughput is similar to the top speed of a car. In reality, you will almost never reach the top...
Louwrentius
Linux: get a list of al disks and their size To get a list of all disk drives of a Linux system, such as this: Disk /dev/md0: 58.0 GB Disk...
over a year ago
5
over a year ago
To get a list of all disk drives of a Linux system, such as this: Disk /dev/md0: 58.0 GB Disk /dev/md1: 2015 MB Disk /dev/md5: 18002.2 GB Disk /dev/sda: 60.0 GB Disk /dev/sdb: 60.0 GB Disk /dev/sdc: 1000.1 GB Disk /dev/sdd: 1000.1 GB Disk /dev/sde: 1000.1 GB Disk /dev/sdf: 1000.1...
Louwrentius
Why VMware vSphere replication is changing the game If you are running a serious VMware environment, chances are you do have a SAN. Often with smaller...
over a year ago
8
over a year ago
If you are running a serious VMware environment, chances are you do have a SAN. Often with smaller setups, many people do employ multiple VMware hosts, but the SAN is a single point of failure. SANs are often fully redundant devices, with redundant PSUs, storage controllers,...
Louwrentius
Personal Security: erase your computer or phone before repair Computer nerds are self sufficient when it comes to fixing their computer. Non-computer experts have...
over a year ago
6
over a year ago
Computer nerds are self sufficient when it comes to fixing their computer. Non-computer experts have to find some other person with greater computer knowledge to repair their computer or phone. That person will then be able to access all data stored on their computer or phone. By...
Louwrentius
Why I bought a digital projector (Panasonic PT-AT5000E) I don't have a TV. I haven't been watching TV for more than 10 years. But I love to watch movies or...
over a year ago
8
over a year ago
I don't have a TV. I haven't been watching TV for more than 10 years. But I love to watch movies or great series like Dexter and Game of Thrones. Until recently, I watched movies or series on my 27" iMac. Twenty-seven inch is large for a computer screen but for a TV, it's quite...
Louwrentius
Experiences running ZFS on Ubuntu Linux 12.04 I really like ZFS because with current data sets, I do believe that data corruption may start...
over a year ago
5
over a year ago
I really like ZFS because with current data sets, I do believe that data corruption may start becoming an issue. The thing is that the license under which ZFS is released does not permit it to be used in the Linux kernel. That's quite unfortunate, but there is hope. There is a...
Louwrentius
Compiling Multicore PAR2 on Ubuntu 12.04 LTS Precise Pangolin If you want to compile PAR2 with multicore support on Linux, it may not work right away from source....
over a year ago
6
over a year ago
If you want to compile PAR2 with multicore support on Linux, it may not work right away from source. I used this version of PAR2 with multicore support. Update 2015: the original link is dead, I foud a copy of the source and put it on my own site here for you to download. First,...
Louwrentius
Setting up a Squid proxy with Clamav anti-virus using c-icap Security is all about a defence-in-depth strategy. Create multiple layers of defence. Every layer...
over a year ago
9
over a year ago
Security is all about a defence-in-depth strategy. Create multiple layers of defence. Every layer presenting a different set of challenges, requiring different skill sets and technology. So every layer will increase the time and effort to compromise your environment. A...
Louwrentius
HP Proliant Microserver N40L is a great NAS or Router Update 2012-12-11: It seems that a new and faster version is on the horizon. Update 2012-12-21:...
over a year ago
11
over a year ago
Update 2012-12-11: It seems that a new and faster version is on the horizon. Update 2012-12-21: Yes, the new model G7 N54L is out. Some products seem almost too good to be true and I think the HP Proliant Microserver N40L is one of them. If you are into the market for a very...
Louwrentius
Fully unattended deployment of Windows clients using limited resources Introduction Anyone who ever installed Windows on a computer by hand must have wished for a solution...
over a year ago
10
over a year ago
Introduction Anyone who ever installed Windows on a computer by hand must have wished for a solution that automate this task. It's just waiting a lot and pressing a button now and then. But installing the operating system itself is only the beginning. Once installed, you need to...
Louwrentius
Understanding Windows KMS and MAK volume license activation Introduction If you have to administer a large number of PCs running Windows, you will end up...
over a year ago
6
over a year ago
Introduction If you have to administer a large number of PCs running Windows, you will end up creating an automated deployment platform for your Windows clients. You may implement something like Windows Deployment Services. I used WDS to create a fully automated installation of...
Louwrentius
Improving web application security by implementing database security Security is about defense-in-depth. It bogles my mind why it is so difficult to implement...
over a year ago
10
over a year ago
Security is about defense-in-depth. It bogles my mind why it is so difficult to implement defense-in-depth security in web applications. 99.9% of applications use a single database account, with root-like privileges. Easiest for the developer of course, and the database is just a...
Louwrentius
Why security is all about defense in depth Many people asume that if you regularly update your computer, you are safe from hackers. But nothing...
over a year ago
8
over a year ago
Many people asume that if you regularly update your computer, you are safe from hackers. But nothing could be further from the truth. Keeping your systems up-to-date only protects you against exploits for publicly known vulnerabilities. Your systems are still not protected...
Louwrentius
Example of a home networking setup with VLANs Updated October 24, 2012, see below. This post is a description of my home network setup based on...
over a year ago
29
over a year ago
Updated October 24, 2012, see below. This post is a description of my home network setup based on gigabit ethernet. I did a non-standard trick with VLANs that may also be of interest to other people. I'm going to start with a diagram of the network. Just take a look (click to...
Louwrentius
Linux Iptables Firewall Script released on Google code I have released LIFS, the Linux Iptables Firewall Script. This script allows you to setup a firewall...
over a year ago
8
over a year ago
I have released LIFS, the Linux Iptables Firewall Script. This script allows you to setup a firewall within minutes. It is easy to use, yet very powerful. It uses Iptables and even improves upon some limitations of Iptables. Every person who has to maintain some kind of...
Louwrentius
Neato XV-15 / XV-11 Robotic Vacuum cleaner review Update 18 February 2012 There is one problem. When the robot is not connected to the charger, the...
over a year ago
8
over a year ago
Update 18 February 2012 There is one problem. When the robot is not connected to the charger, the batteries are depleted very fast. Even if the batteries are not entirely depleted and the robot can still display the menu, the clock loses it's time. Every time the robot gets a too...
Louwrentius
Speeding up Linux MDADM RAID array rebuild time using bitmaps Update 2020: Please beware of the impact of random write I/O performance. Please note that with a...
over a year ago
6
over a year ago
Update 2020: Please beware of the impact of random write I/O performance. Please note that with a modern Linux distribution, bitmaps are enabled by default. They will not help speed up a rebuild after a failed drive. But it will help resync an array that got out-of-sync due to...
Louwrentius
Setting up a VPN with your iPhone using L2TP, IPSec and Linux This blogpost discusses how to setup an IPSec-based VPN between your iPhone and a Linux server....
over a year ago
6
over a year ago
This blogpost discusses how to setup an IPSec-based VPN between your iPhone and a Linux server. Updated 16 October 2012 - now compatible with Ubuntu 12.04 LTS IMPORTANT! (update January 2013) I find using OpenVPN with the new iOS OpenVPN client a way better solution. OpenVPN...
Louwrentius
Is there an easy and secure way to transfer files? Many organisations just assume that the local physical network is trusted. That their network...
over a year ago
7
over a year ago
Many organisations just assume that the local physical network is trusted. That their network equipment is physically secure and that it is impossible for an attacker to get on the wire and start eavesdropping on network traffic. Many organisations do not seem too concerned about...
Louwrentius
Script that deletes old files to keep disk from filling up When a disk has no free space left, all kinds of trouble can occur. Therefore, I've created a...
over a year ago
9
over a year ago
When a disk has no free space left, all kinds of trouble can occur. Therefore, I've created a script that monitors the used space of a volume and deletes the oldest file if a certain threshold is reached. The script will keep on deleting the oldest file present on disk until...
Louwrentius
Lion's FileVault does not support Bootcamp and external boot disks Read the comments as they may provide useful information for your particular situation I boot my...
over a year ago
6
over a year ago
Read the comments as they may provide useful information for your particular situation I boot my iMac from an external FW800 SSD. I found out that it is impossible to encrypt this disk using the new FileVault as part of Lion. Furthermore, I also found out that if you have a disk...
Louwrentius
Lion's Disk Utility not compatible with CoreStorage and Filevault My 1 TB hard drive of my 2011 27" iMac was partitioned with: A bootable partition with Mac OS X...
over a year ago
6
over a year ago
My 1 TB hard drive of my 2011 27" iMac was partitioned with: A bootable partition with Mac OS X Lion Time machine partition (I use an external SSD as my main OS) Bootcamp partition with windows A data partition containg... data. The problem is that CoreStorage is too new. Disk...
Louwrentius
Achieving 220 MB/s network file transfers using Linux Bonding I wrote an article about the subject of getting beyond the limits of gigabit network file transfers....
over a year ago
7
over a year ago
I wrote an article about the subject of getting beyond the limits of gigabit network file transfers. My solution is to use multiple gigabit network cards and use Linux interface bonding to create virtual 2 gigabit network interfaces. The solution is to use mode 0 or round robin...
Louwrentius
Additional proof that Apple is ditching the optical drive I'm a strong advocate of killing the optical drive. As of 2011, there is no need for it anymore....
over a year ago
5
over a year ago
I'm a strong advocate of killing the optical drive. As of 2011, there is no need for it anymore. Laptops could get lighter, smaller or have more room for additional battery capacity if the optical drive would no longer be present. In my life, I never see people use the optical...
Louwrentius
Cheap solution for putting an SSD in an iMac If you want to order a new iMac with an SSD there are two problems: An SSD of 256 gigabytes will...
over a year ago
7
over a year ago
If you want to order a new iMac with an SSD there are two problems: An SSD of 256 gigabytes will cost you a lot: 600 euros. The SSD is of medium quality, and does not justify the cost of 600 euros. Here you can find information about the Toshiba SSD that Apple provides. You can...
Louwrentius
Switching away from Debian to Ubuntu LTS Over the last couple of years, Debian Linux has released new stable versions about every two years....
over a year ago
6
over a year ago
Over the last couple of years, Debian Linux has released new stable versions about every two years. This pace is great for progress, but there is a serious problem. This problem is related to their support for older Debian stable versions. If you read the quote below from the...
Louwrentius
Cannot access Windows guest within VMware Fusion when running vsphere client Currently, I am running VMware ESXi 4.1 on a test system. To manage ESXi, you need the VSphere...
over a year ago
8
over a year ago
Currently, I am running VMware ESXi 4.1 on a test system. To manage ESXi, you need the VSphere client, which is only available for the Windows platform. Therefore, I run VMware Fusion on my Mac to be able to access VSphere and manage my ESXi host. The trouble is that both ESXi...
Louwrentius
Performance monitoring using dstat I'd like to introduce the utility 'dstat'. Dstat provides detailed statistics about what is...
over a year ago
10
over a year ago
I'd like to introduce the utility 'dstat'. Dstat provides detailed statistics about what is currently happening on your Linux box. Dstat allows you to monitor the system load, disk troughput, disk io, network bandwith, and many more items. Dstat is so valuable because it...
Louwrentius
Determining smartphone market share using wireless sniffing I started a project to see if I could track smartphone users by sniffing for wifi-clients. Most...
over a year ago
8
over a year ago
I started a project to see if I could track smartphone users by sniffing for wifi-clients. Most smartphones support wifi and most people don't bother disabling wifi when they go outdoors1. If wifi is left on, it is possible to detect these smartphones and track their movement. To...
Louwrentius
Buying a new computer *** Desktop or Laptop *** When deciding on which computer to buy, the first decision you have to...
over a year ago
9
over a year ago
*** Desktop or Laptop *** When deciding on which computer to buy, the first decision you have to make is about whether to go for a desktop or a laptop. There was a time that many believed that the desktop would become a niche product. Most people want a laptop because they can...
Louwrentius
Why I do not use ZFS as a file system for my NAS Many people have asked me why I do not use ZFS for my NAS storage box. This is a good question and I...
over a year ago
7
over a year ago
Many people have asked me why I do not use ZFS for my NAS storage box. This is a good question and I have multpile reasons why I do not use ZFS and probably never will. ** A lot has changed since this article was first published. I do now recommend using ZFS. I've also based my...
Louwrentius
Thunderbolt, a cheap high-speed storage interconnect? Intel and Apple released Thunderbolt a high-speed (10 Gigabit/s) interface, that seems to replace...
over a year ago
8
over a year ago
Intel and Apple released Thunderbolt a high-speed (10 Gigabit/s) interface, that seems to replace both USB and Firewire. It is mainly targeted at end-user systems allowing to connect peripherals with just a single cable to a computer. Thunderbolt devices, like external hard...
Louwrentius
Setting up a Jabber instant messaging server |_http-title: Site doesn't have a title (text/html;... I wanted to see how dificult it is to setup an instant messaging server based on open source...
over a year ago
9
over a year ago
I wanted to see how dificult it is to setup an instant messaging server based on open source software. Now I know that it is very easy, unless you are stubborn and do things your own way. In this example, I'm setting up a small IM server that is only for internal company use, but...
Louwrentius
Parallel / distributed password cracking with John the Ripper and MPI This article has been updated to reflect the changes for John version 1.7.8 as released in june...
over a year ago
7
over a year ago
This article has been updated to reflect the changes for John version 1.7.8 as released in june 2011. The most important change is the fact that MPI support is now integrated in the jumbo patch. The original John the Ripper off-line password cracker only uses a single processor...
Louwrentius
The downside of 120 Mbit broadband internet My Dutch ISP Ziggo provides internet access through DOCSIS cable modems. They are now capable of...
over a year ago
8
over a year ago
My Dutch ISP Ziggo provides internet access through DOCSIS cable modems. They are now capable of providging 120 Mbit downstream and 10 Mbit upstream, for an affordable price. In a way this is mind boggling. Most people have 100 Mbit home networks that are not capable of handling...
Louwrentius
'Improved' image gallery for Blogofile This blog is just static HTML pages that are generated using Blogofile. The Blogofile website sports...
over a year ago
8
over a year ago
This blog is just static HTML pages that are generated using Blogofile. The Blogofile website sports a small image gallery that has been written to illustrate how to create your own 'controllers' or Blogofile plugins. My Python skills are horrible buy I managed to improve a bit...
Louwrentius
Firewire: the forgotten security risk The battle between Firewire and USB has been won by USB, but Firewire is still arround. It is not...
over a year ago
7
over a year ago
The battle between Firewire and USB has been won by USB, but Firewire is still arround. It is not that prevalent, cheap computers lack Firewire, but they often have a PCMCIA slot. The thing is this: Firewire allows direct access to all RAM of your computer. An attacker...
Louwrentius
Some pretty NAS case designs If you are planning on building your own NAS box, I have some suggestions regarding the case. In my...
over a year ago
4
over a year ago
If you are planning on building your own NAS box, I have some suggestions regarding the case. In my opinion, most computer case designers have absolutely no taste. Antec and Lian Li do create nice cases, but not that spectacular. And Lian Li is just very expensive. A fairly new...
Louwrentius
Migration from blogger to blogofile and disqus is complete As stated in my previous post, I migrated all posts from blogger.com to my own host running...
over a year ago
9
over a year ago
As stated in my previous post, I migrated all posts from blogger.com to my own host running blogofile. At the time of my previous post, I was not able to restore all comments made on my old blog. Thanks to some help from disqcus I fixed an error on my behalf and all old comments...
Louwrentius
Migrated this blog from blogger.com to blogofile Until now, I was hosting my blog on Google's blogger. I switched to using Blogofile. I wanted to...
over a year ago
9
over a year ago
Until now, I was hosting my blog on Google's blogger. I switched to using Blogofile. I wanted to have more control over my content and the layout. I had many issues with the blogger blog post editor, resulting in ugly posts with too much white space, strange fonts and fonts...
Louwrentius
LFS - Linux Firewall Script released I started a small new Google project for a new script I wrote called LFS. It stands for Linux...
over a year ago
5
over a year ago
I started a small new Google project for a new script I wrote called LFS. It stands for Linux Firewall Script. I run a small Linux box as an internet router that doubles as a firewall. The firewall is configured using iptables. In my opinion, iptables is not the easiest tool to...
Louwrentius
Why filtering DHCP traffic is not always possible with iptables When configuring my new firewall using iptables, I noticed something very peculiar. Even if all...
over a year ago
8
over a year ago
When configuring my new firewall using iptables, I noticed something very peculiar. Even if all input, forward and output traffic was dropped, DHCP traffic to and from my DHCP server was not blocked even if there were no rules permitting this traffic. I even flushed all rules,...
Louwrentius
Belkin Gigabit USB 2.0 adapter works perfectly with Linux My ISP upgraded my internet connection speed to a whopping 120 Mbit. I am using a mac mini as my...
over a year ago
7
over a year ago
My ISP upgraded my internet connection speed to a whopping 120 Mbit. I am using a mac mini as my internet router. As you may be aware, the mini has only one network interface, so I added a second interface using a USB to ethernet adapter. This adapter was limited to 100 Mbit, so...
Louwrentius
The minimum requirements for a secure system The most secure server system is a system that is not connected to a network and turned off....
over a year ago
5
over a year ago
The most secure server system is a system that is not connected to a network and turned off. However, little work seems to be getting done this way. So we want to turn systems on and connect them to a network, or even (God forbid) the internet. The thing is this. A system...
Louwrentius
'Linux: using disk labels to counter storage device name changes' My router decided to change the device name for some USB storage devices. So /dev/sdc was swapped...
over a year ago
8
over a year ago
My router decided to change the device name for some USB storage devices. So /dev/sdc was swapped for /dev/sdd and vice versa. The result was some file system corruption on /dev/sdc, because it was used on a remote system through iSCSI, using a different file system from...
Louwrentius
'Secure programming: how to implement user account management' Most web applications work like this: The application uses a single database account to perform all...
over a year ago
7
over a year ago
Most web applications work like this: The application uses a single database account to perform all actions. Users are just some records in a table. Account privileges and roles are part of this table, or separate tables. This implies that all security must be designed and build...
Louwrentius
Do not buy a hardware RAID controller for home use Hardware RAID controllers are considered 'the best' solution for high performance and high...
over a year ago
6
over a year ago
Hardware RAID controllers are considered 'the best' solution for high performance and high availability. However, this is not entirely true. Using a hardware RAID controller might even endanger your precious data. For enterprise environments, where performance is critical, it is...
Louwrentius
Linux network interface bonding / trunking or how to get beyond 1 Gb/s This article discusses Linux bonding and how to achieve 2 Gb/s transfer speeds with a single TCP/UDP...
over a year ago
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over a year ago
This article discusses Linux bonding and how to achieve 2 Gb/s transfer speeds with a single TCP/UDP connection. UPDATE July 2011 Due to hardware problems, I was not able to achieve transfer speeds beyond 150 MB/s. By replacing a network card with one from another vendor (HP...
Louwrentius
The iPhone, iPad and iOS are powering a revolution Most people just don't understand computers. Are these people dumb? Some may be dumb, but the people...
over a year ago
6
over a year ago
Most people just don't understand computers. Are these people dumb? Some may be dumb, but the people who make them are maybe even dumber. Because they can't seem to figure out how to create a computer that the majority of people understand. When the original macintosh arrived at...
Louwrentius
Apple is killing off the optical drive just like the floppy disk With the release of the new MacBook Air we are one step closer to killing off the cd-rom and the...
over a year ago
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over a year ago
With the release of the new MacBook Air we are one step closer to killing off the cd-rom and the dvd. As with the previous MacBook Air, this device has no optical drive. And that is a good thing. People do not need an optical drive. You have the network and you have USB disks....
Louwrentius
Linux Software RAID benchmarking script Just a small post. To benchmark your Linux software RAID array as setup with MDADM, please use...
over a year ago
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over a year ago
Just a small post. To benchmark your Linux software RAID array as setup with MDADM, please use my new benchmark script. I used this script to create these results. You may need to configure some values within the header of this file to make it fit your enviroment. ...
Louwrentius
'Zabbix Security: client-server communication seems insecure' Zabbix is a populair tool for monitoring servers, services and network equipment. For monitoring...
over a year ago
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over a year ago
Zabbix is a populair tool for monitoring servers, services and network equipment. For monitoring hosts, Zabbix provides an agent that can be installed on the hosts that must be monitored. Based on the supplied documentation and some remarks on the internets, the 'security' of...
Louwrentius
Debian Lenny and Dell R410 network card not supported For those who are running Debian Lenny and want to order the new Dell R410 server, beware! There is...
over a year ago
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over a year ago
For those who are running Debian Lenny and want to order the new Dell R410 server, beware! There is no safe solution to get Debian Lenny working with the on-board Broadcom network cards. A fairly recent kernel is required. Basically, you will have to install back-ported kernels,...
Louwrentius
Solaris is an obsolete platform Assuming that the rumor is true and OpenSolaris will be slain by Oracle, we must conclude that the...
over a year ago
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over a year ago
Assuming that the rumor is true and OpenSolaris will be slain by Oracle, we must conclude that the Solaris operating system is obsolete. Solaris can be considered legacy. Sun was a hardware shop and to sell their hardware, they needed a great operating system. Sun had a great...
Louwrentius
The future of ZFS now that OpenSolaris is dead With the probable loss of OpenSolaris, there may be another, maybe more devastating loss. The very...
over a year ago
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over a year ago
With the probable loss of OpenSolaris, there may be another, maybe more devastating loss. The very popular and very advanced Zetabyte File System (ZFS) The only open source platform that actively supports ZFS is FreeBSD. And they just 'copied' the code from OpenSolaris. Are they...
Louwrentius
RAID 5 vs. RAID 6 or do you care about your data? Storage is cheap. Lots of storage with 10+ hard drives is still cheap. Running 10 drives increases...
over a year ago
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over a year ago
Storage is cheap. Lots of storage with 10+ hard drives is still cheap. Running 10 drives increases the risk of a drive failure tenfold. So often RAID 5 is used to keep your data up and running if one single disks fails. But disks are so cheap and storage arrays are getting so...
Louwrentius
'A Moment Of Silence: OpenSolaris Is Dead' The last release of OpenSolaris dates back to July 2009. The next release was scheduled for March...
over a year ago
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over a year ago
The last release of OpenSolaris dates back to July 2009. The next release was scheduled for March 2010, but Oracle did not release anything. It is dead silent around OpenSolaris. On 12 July 2010, the OpenSolaris Government Board sent out an ultimatum to Oracle: "please...
Louwrentius
Compiling Handbrake CLI on Debian Lenny In this post I will show you how to compile Handbrake for Debian Lenny. Please note that although...
over a year ago
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over a year ago
In this post I will show you how to compile Handbrake for Debian Lenny. Please note that although the Handbrake GUI version does compile on Lenny, it crashes with a segmentation fault like this: Gtk: gtk_widget_size_allocate(): attempt to allocate widget with width -5 and height...
Louwrentius
Debian Lenny and Dell S300 H200 and H700 RAID controllers update november 2010: it is reported in the comments that the next release will support these...
over a year ago
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over a year ago
update november 2010: it is reported in the comments that the next release will support these controllers. However, which controllers are supported is not clear. Also, we may have to wait for quite some time before squeeze will be released. Just a quick note: it seems that the...
Louwrentius
Lustre and the risk of Serious Data Loss Personally I have a weakness for big-ass storage. Say 'petabyte' and I'm interested. So I was...
over a year ago
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over a year ago
Personally I have a weakness for big-ass storage. Say 'petabyte' and I'm interested. So I was thinking about how you would setup a large, scalable storage infrastructure. How should such a thing work? Very simple: you should be able just to add hosts with some bad-ass huge...
Louwrentius
Secure caching DNS server on Linux with DJBDNS The most commonly used DNS server software is ISC BIND, the "Berkeley Internet Name Daemon"....
over a year ago
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over a year ago
The most commonly used DNS server software is ISC BIND, the "Berkeley Internet Name Daemon". However, this software has a bad security track record and is in my opinion a pain to configure. Mr. D.J. Bernstein developed "djbdns", which comes with a guarantee: if anyone finds a...
Louwrentius
'Linux RAID level and chunk size: the benchmarks' Introduction When configuring a Linux RAID array, the chunk size needs to get chosen. But what is...
over a year ago
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over a year ago
Introduction When configuring a Linux RAID array, the chunk size needs to get chosen. But what is the chunk size? When you write data to a RAID array that implements striping (level 0, 5, 6, 10 and so on), the chunk of data sent to the array is broken down in to pieces, each part...
Louwrentius
'Tool of the month: iftop - advanced bandwidth monitoring' The utility iftop allows you to monitor bandwidth usage. It is in some sense similar to tools like...
over a year ago
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over a year ago
The utility iftop allows you to monitor bandwidth usage. It is in some sense similar to tools like iptraf, dstat and bwm-ng. Iftop is more special than those. Because iftop lets you monitor the speed of individual TCP / UDP connections. Basically, you will be able to determine...
Louwrentius
WFS - WAN Failover Script now available Since I could not find a WAN failover script for Linux to my likening, I wrote one myself. If you...
over a year ago
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over a year ago
Since I could not find a WAN failover script for Linux to my likening, I wrote one myself. If you have any use for it: I put it on a Google code project. WFS tests the availability of your primary WAN connection and switches to your secondary / backup connection when a failure is...
Louwrentius
HP Procurve "auto DoS" feature causing network problems A feature on more recent HP Procurve models (18xx series, such as 1810G etc.) is called "Auto DoS"....
over a year ago
6
over a year ago
A feature on more recent HP Procurve models (18xx series, such as 1810G etc.) is called "Auto DoS". You can find it in the section "Security" and then "Advanced security". If you enable the Auto DoS feature, traffic is blocked based on one of these conditions: the source port...
Louwrentius
RAID array size and rebuild speed When a disk fails of a RAID 5 array, you are no longer protected against (another) disk failure and...
over a year ago
6
over a year ago
When a disk fails of a RAID 5 array, you are no longer protected against (another) disk failure and thus data loss. During this rebuild time, you are vulnerable. The longer it takes to rebuild your array, the longer you are vulnerable. Especially during a disk-intensive period,...
Louwrentius
'Linux: monitor a directory for files' Inotify is a mechanism in the Linux kernel that reports when a file system event occurs. The...
over a year ago
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over a year ago
Inotify is a mechanism in the Linux kernel that reports when a file system event occurs. The inotifywait comand line utility can be used in shell scripts to monitor directories for new files. It can also be used to monitor files for changes. Inotifywait must be installed and is...
Louwrentius
'Syslog: the hidden security risk' People sometimes forget that there are also a number of UDP-based services that may pose a threat to...
over a year ago
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over a year ago
People sometimes forget that there are also a number of UDP-based services that may pose a threat to the security of your systems. SNMP is a well-known service, notorious for being configured with a default password (or community string). But there is another service that is...
Louwrentius
Ubuntu and full disk encryption (FDE) Ubuntu is based on Debian Linux. As part of a regular Debian installation, you can choose to create...
over a year ago
4
over a year ago
Ubuntu is based on Debian Linux. As part of a regular Debian installation, you can choose to create an encrypted disk volume based on LUKS. This is different from the option within the Ubuntu installation to encrypt home directories. To be able to install Ubuntu and use full disk...
Louwrentius
Scanning many hosts in parallel with Nmap using PPSS Scanning a large number of hosts using Nmap often takes a lot of time. During this time, no output...
over a year ago
9
over a year ago
Scanning a large number of hosts using Nmap often takes a lot of time. During this time, no output is written to a file or disk. Only when Nmap is finished, is all output written to the output file. Often, I want to start processing results of hosts that have already been...
Louwrentius
Corsair CM PSU-750HX seems ok I had to replace my Coolermaster PSU and after some searching on the interweb, I chose the Corsair...
over a year ago
6
over a year ago
I had to replace my Coolermaster PSU and after some searching on the interweb, I chose the Corsair CMPSU-750HX. One of the reasons is that Corsair states that this PSU can withstand 50 degree Celcius in continuous operation on full load. The package is very, clean, with all the...
Louwrentius
Smoking coolermaster Silent Pro M 600W TN6M50 So I was just messing around on my work station, when suddenly I smelled the smell any person...
over a year ago
8
over a year ago
So I was just messing around on my work station, when suddenly I smelled the smell any person familiar with electronics fears. The smell of some electrical component burning. The whole upper floor smelled like something was smoldering. So I shut down both my storage servers....
Louwrentius
Is the iPhone OS a threat to our freedom? There is one fundamental flaw with both the iPhone and the iPad. As a user, you do not have full...
over a year ago
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over a year ago
There is one fundamental flaw with both the iPhone and the iPad. As a user, you do not have full control over your device. You can only install or run software that is approved by Apple. This is something that is unprecedented. All major platforms, Windows, Linux, Mac OS X do...
Louwrentius
Why the iPad will be a breakthrough in human computing The fact is that computers aren't made for humans. Computers are just made, and humans have to...
over a year ago
6
over a year ago
The fact is that computers aren't made for humans. Computers are just made, and humans have to adjust to them. The problem is that most people that are not into technology just don't understand how computers work. Should I single click of double click? Click left or right? The...
Louwrentius
The iPad will be the death of Flash So Apple finally released their tablet computer: the iPad. One of the most debated drawbacks is that...
over a year ago
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over a year ago
So Apple finally released their tablet computer: the iPad. One of the most debated drawbacks is that it lacks support for Adobe Flash. The iPhone does not support Flash either, and since the iPad is based on the iPhone OS, this should not come as a surprise. Now many people see...
Louwrentius
Mounting a file system or partition from a disk image You cannot just make a disk copy with dd and then just mount it as a regular disk. You must know...
over a year ago
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over a year ago
You cannot just make a disk copy with dd and then just mount it as a regular disk. You must know where the partition starts on the disk. So first, you need to get the partition table with sfdisk: sfdisk -l -uS image_file.dd The output is something like: Disk...
Louwrentius
'Linux: show graphical layout of disk temperatures' graphic, representation To get a visual representation of hard drive temperatures, I wrote a...
over a year ago
7
over a year ago
graphic, representation To get a visual representation of hard drive temperatures, I wrote a small script. The output of this script looks like this: This output is tailored to the exact disk lay-out of my storage server. However, it is also usable for other servers. You have to...
Louwrentius
Recovering a lost partition using gpart Even today people do not understand how important it is for the safety of your data to make backups....
over a year ago
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over a year ago
Even today people do not understand how important it is for the safety of your data to make backups. I was asked to perform some data recovery on a hard drive of an old computer, which still contained important documents and photo's. The first thing I did was to make a disk image...
Louwrentius
Wake On Lan not working with realtek r8168 card After messing around with different kernels on Debian Lenny, I noticed that my system did no longer...
over a year ago
7
over a year ago
After messing around with different kernels on Debian Lenny, I noticed that my system did no longer respond to WOL packets. The system is using an on-board Realtek R8168 chip which supports wake on lan. After searching and reading i found the problem. The system is using an...
Louwrentius
Shunit2, unit testing for shell scripts This may be of interest to people who are as stupid as I am and write elaborate shell scripts...
over a year ago
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over a year ago
This may be of interest to people who are as stupid as I am and write elaborate shell scripts instead of using a proper scripting language such as Python or Ruby. No I am deliberately not mentioning Perl here. Anyway, testing is always an issue. With PPSS, I encountered many...
Louwrentius
Google DNS - what to think of it? Google now provide an open DNS service. At first I was scared that they use their service to get...
over a year ago
7
over a year ago
Google now provide an open DNS service. At first I was scared that they use their service to get information about users. However, their privacy statement tells us that no personal identifiable information is stored for longer than 48 hours. The permanent logs do not contain such...
Louwrentius
Convert dos file to linux format wit vim If you have some file that has been saved on a (Win)do(w)s host you may notice that all lines end...
over a year ago
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over a year ago
If you have some file that has been saved on a (Win)do(w)s host you may notice that all lines end with ^M. To fix this, you can use the tool dos2unix. If however this tool is not at your disposal, you may have a problem. If vim is available, you do not have a problem: The trick...
Louwrentius
Which file system for a large storage array under Linux? There are many file systems available under Linux, however only a few of them can be used for a...
over a year ago
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over a year ago
There are many file systems available under Linux, however only a few of them can be used for a large storage array. I am assuming that you want to create a single file system. I don't care if you use LVM or other layers beneath, this is about which file system to use. I will...
Louwrentius
'Tip of the day: Scrolling in GNU screen' Just the answer: By default, on Debian, the scroll back buffer is about 1K lines. This can...
over a year ago
6
over a year ago
Just the answer: By default, on Debian, the scroll back buffer is about 1K lines. This can be changed in the .screenrc file in your home directory. The following example sets the scroll back buffer to 5K lines. defscrollback 5000 Set the scroll back buffer on the fly with: First...
Louwrentius
'Gzip with parallel compression support: pigz' The speed at which files are compressed with gzip is currently almost always determined by the speed...
over a year ago
8
over a year ago
The speed at which files are compressed with gzip is currently almost always determined by the speed of the CPU. However, standard unix gzip is single- threaded and only uses a single CPU (core). However, the maintainer of the zlib library has released 'pigz' or 'pig-zee' whichs...
Louwrentius
How to determine which process causes IO ? There is a nifty little program called 'iotop'. Iotop is part of Debian or Ubuntu and can be...
over a year ago
9
over a year ago
There is a nifty little program called 'iotop'. Iotop is part of Debian or Ubuntu and can be installed with a simple apt-get. Once you have determined with 'top' that the system is waiting on IO-access, It is nice to know which process is responsibe for this IO. Therefore, you...
Louwrentius
Making cowpatty recognize a four-way handshake I was unable to get cowpatty working with a packet capture that actually contains a four-way...
over a year ago
9
over a year ago
I was unable to get cowpatty working with a packet capture that actually contains a four-way handshake of a WPA session. I got it working like this: First, download cowpatty 4.6 right here, within the source directory of cowpatty. Extract cowpatty and apply this patch using these...
Louwrentius
Monitor power usage with your UPS If a system is connected to a UPS (Uninterruptible Power Supply), it is possible to determine how...
over a year ago
6
over a year ago
If a system is connected to a UPS (Uninterruptible Power Supply), it is possible to determine how much power it consumes. For this purpose, I wrote a small script: Host:~# ./ups.sh UPS model: Back-UPS RS 1200 LCD APC model: Back-UPS RS 1200 LC Capacity: 720 Watt Load: 18...
Louwrentius
24 TB based on Norco RPC-4020 and Linux Software RAID Just a quick link: Some person build basically the same setup, including identical...
over a year ago
8
over a year ago
Just a quick link: Some person build basically the same setup, including identical controller, providing 28 TB of storage: Take a look here The main difference is that this person uses 1.5 TB disk, thus achieving more storage.
Louwrentius
Debian Linux Preseeding - an installation framework Look Ma! No hands! just watching a system PXE-boot and install itself into a fully...
over a year ago
8
over a year ago
Look Ma! No hands! just watching a system PXE-boot and install itself into a fully operational system is fun. PXE boot and preseeding is not enough however to accomplish this. By itself, preseeding only installs a basic operating system. Next, you need to configure all sorts of...
Louwrentius
Linux Mac Mini - temperature monitoring with lm-sensors This post is about getting temperature monitoring to work with a Mac Mini running Linux. Using...
over a year ago
10
over a year ago
This post is about getting temperature monitoring to work with a Mac Mini running Linux. Using Debian Lenny, out of the box, lm-sensors is not working. No sensors can be found. This is how temperature monitoring and fan speed monitoring can be made to work: modprobe applesmc If...
Louwrentius
Linux on Mac Mini - boot after power failure When using a Mac Mini as a server or router, it is very nice if the machine automatically boots if a...
over a year ago
7
over a year ago
When using a Mac Mini as a server or router, it is very nice if the machine automatically boots if a power failure has occurred. User chirhoxi on the ubuntu forum found out how this can be achieved: http://ubuntuforums.org/showthread.php?t=1209576 Basically you need one of these...
Louwrentius
How to run Debian Linux on an Intel based Mac Mini The Mac Mini is just a gorgeous device. It is beautiful, small, silent, powerfull yet energy...
over a year ago
5
over a year ago
The Mac Mini is just a gorgeous device. It is beautiful, small, silent, powerfull yet energy efficient. When idle, it uses around 20 watts. I'm using one of the first Intel-based Minis with an Intel Core Duo chip, running at 1.6 Ghz. I want to use this mini as an expensive router...
Louwrentius
The security risk of vendor-supplied default SSL certificates Often, software comes supplied with some default SSL certificate, for testing purposes, such as...
over a year ago
7
over a year ago
Often, software comes supplied with some default SSL certificate, for testing purposes, such as those 'snake oil' certificates (they are called snake oil certificates for a reason). In practice, I often encounter usage of such certificates. People may seem to think that as long...
Louwrentius
Blu Ray is dead HD-DVD may be dead, but Blu Ray is just as dead. The whole concept of optical media is dead....
over a year ago
8
over a year ago
HD-DVD may be dead, but Blu Ray is just as dead. The whole concept of optical media is dead. Honestly, who is still burning CD's or DVD's nowadays? (If you are, why for Christ sake? I can't think of a single good reason) And at 10 euros ($100) for a single Blu Ray disk, you must...
Louwrentius
PPSS version 2.30 now operates asynchronous If you background a bash or shell process, how do you determine if it has finished? Since inter...
over a year ago
7
over a year ago
If you background a bash or shell process, how do you determine if it has finished? Since inter process communication is not possible using shell scripts, people often refer to while loops or other polling mechanisms to determine if some process has stopped. However, the one...
Louwrentius
Laptop or netbook as router? If you want a router for distribution of internet to your computers at home, there are several...
over a year ago
3
over a year ago
If you want a router for distribution of internet to your computers at home, there are several options. buy some embedded device from Linksys, Draytek, Asus, 3com, ZyXtel or netgear This type of hardware is cheap, economical, and gets you up and running in a few minutes. The...
Louwrentius
How to build an energy efficient computer for home use In short: Buy whatever you fucking want. Turn the fucking thing off when you're not using...
over a year ago
6
over a year ago
In short: Buy whatever you fucking want. Turn the fucking thing off when you're not using it. Long: People are spending a lot of time building an energy efficient home computer, that can act as an HTPC, NAS, or whatever. It must consume as little power as possible, because it it...
Louwrentius
Visual representation of hard drives and their temperature If you build a NAS with many drives, it may be of interest to you which drives get hot and where...
over a year ago
5
over a year ago
If you build a NAS with many drives, it may be of interest to you which drives get hot and where they are located in the chassis. My Norco 4020 case has twenty drives in RAID 6, plus two operating system drives in RAID 1. I wrote a script that shows me the temperature of each...
Louwrentius
'Linux: obtain motherboard model / type and vendor' If you want to know what motherboard is installed in a system, use the tool dmidecode: dmidecode |...
over a year ago
7
over a year ago
If you want to know what motherboard is installed in a system, use the tool dmidecode: dmidecode | grep -e "Manufacturer|Product" | head -n 4 | tail -n 2 The result might be something like: Manufacturer: ASUSTeK Computer INC. Product Name: P5Q-EM DO Manufacturer: ASUSTeK Computer...
Louwrentius
'lm-sensors: hardware monitoring with the w83627ehf module' I have two systems that use the w83627ehf driver for hardware monitoring. However, if this driver is...
over a year ago
8
over a year ago
I have two systems that use the w83627ehf driver for hardware monitoring. However, if this driver is installed with a regular modprobe like: modprobe w83627ehf The result will be: FATAL: Error inserting w83627ehf (/lib/modules/2.6.28-1-amd64/kernel/drivers/hwmon/w83627ehf.ko):...
Louwrentius
Using ncat to provide SSL-support to non-ssl capable software Sometimes, people are using software that does not support encrypted connections using SSL. To...
over a year ago
7
over a year ago
Sometimes, people are using software that does not support encrypted connections using SSL. To provide SSL-support to such a client, ncat can be used. Ncat is part of nmap, the famous port-scanner. The main principle is that the non-ssl capable software does not connect to the...
Louwrentius
Howto get the hard disk size under Linux? A: There is no single tool for this job, but it seems that Fdisk is just fine: server:~# fdisk -l 2>...
over a year ago
6
over a year ago
A: There is no single tool for this job, but it seems that Fdisk is just fine: server:~# fdisk -l 2> /dev/null | grep Disk | grep -v identifier Disk /dev/sda: 500.0 GB, 500028145664 bytes Disk /dev/sdb: 500.0 GB, 500028145664 bytes Disk /dev/sdc: 1000.1 GB, 1000123400192...
Louwrentius
20 disk 18 TB RAID 6 storage based on Debian Linux This system is no longer operational and has been decomissioned (2017) This is my NAS storage server...
over a year ago
6
over a year ago
This system is no longer operational and has been decomissioned (2017) This is my NAS storage server based on Debian Linux. It uses software RAID and 20 one terrabyte hard drives. It provides a total usable storage capacity of 18 terrabytes in a single RAID 6 array. One of the...
Louwrentius
HighPoint RocketRAID and staggered spinup with Samsung F1 I have experienced problems using a HighPoint RocketRaid 2320 and 2340 when they are using...
over a year ago
8
over a year ago
I have experienced problems using a HighPoint RocketRaid 2320 and 2340 when they are using 'staggered spinup' in combination with Samsung Spinpoint F1, 1 (one) terrabyte disks. The problem is that the F1 disks spinup very slowly and often seem to 'hang' while making ticking...
Louwrentius
8 TB RAID 6 Linux software RAID using EXT4 Mobo: Asus P5Q-EM DO ( 6x sata) CPU: Core 2 Duo E7400 RAM: 4 GB Controller; HighPoint RocketRAID...
over a year ago
4
over a year ago
Mobo: Asus P5Q-EM DO ( 6x sata) CPU: Core 2 Duo E7400 RAM: 4 GB Controller; HighPoint RocketRAID 2314 (16x poorten) PSU: CooMas Silent Pro M 600W ATX2 (definitely not overkill) HD: Samsung 1 TB SAT2 HD103UJ (10x) OS: Debian Lenny with custom kernel (backported) FS: EXT4 RAID...
Louwrentius
Script that shows ETA of RAID rebuild / reshape I made a small script that converts the output of cat /proc/mdstat to an actual date and time...
over a year ago
8
over a year ago
I made a small script that converts the output of cat /proc/mdstat to an actual date and time telling you when the RAID rebuild / reshape is finished. This is the link to the correct version of the script. Example: debian:~# ./raid-rebuild-eta.sh Estimated time of finishing...
Louwrentius
Linux RAID 6 performance using software RAID So after toying around with RAID 0 just for fun, time to get serious. I created a RAID 6 of 10 x 1...
over a year ago
7
over a year ago
So after toying around with RAID 0 just for fun, time to get serious. I created a RAID 6 of 10 x 1 TB disks. This gives me raw device read speeds of 850 MB/s and write speeds of 300 MB/s. I think this is exactly what should be expected, but boy it is damn fast. Especially the...
Louwrentius
1.0 GB/s using Linux software RAID I filled the Norco case with hardware. It is now up and running, based on Debian Linux (Lenny). I...
over a year ago
8
over a year ago
I filled the Norco case with hardware. It is now up and running, based on Debian Linux (Lenny). I immediately performed some initial tests with software RAID 0. The results are just astounding. debian:~# dd if=/dev/md0 of=/dev/null bs=1M count=50000 50000+0 records in 50000+0...
Louwrentius
Got myself a Norco RPC-4020 I've got this fetish for storage. So I bought a case that gives me some room for future expantion....
over a year ago
5
over a year ago
I've got this fetish for storage. So I bought a case that gives me some room for future expantion. The current 6 TB RAID 6 storage server does not have any room for expantion. This Norco RPC-4020 case with 20 hot swap drive bays does however. Don't know what to fill it with yet.
Louwrentius
Bash Shell Function Library (BSFL) released. The Bash Shell Function Library (BSFL) is a small Bash script that acts as a library for bash...
over a year ago
7
over a year ago
The Bash Shell Function Library (BSFL) is a small Bash script that acts as a library for bash scripts. It provides a couple of functions that makes the lives of most people using shell scripts a bit easier. The purpose of this library is to provide pre-build functions for...
Louwrentius
'Tip of the day for every Linux or Unix user: brace expantion' Searching the web I discovered some really nice feature of the unix shell, which I didn't know...
over a year ago
7
over a year ago
Searching the web I discovered some really nice feature of the unix shell, which I didn't know about. Try this: touch foobar.conf Now try this: cp foobar.conf{,.bak} It is equivalent to: cp foobar.conf foobar.conf.bak This is also the easiest way to create sequences. Do not use...
Louwrentius
Compatibility Highpoint RocketRAID 2320 and Samsung Spinpoint F1 There are some reports about incompatibility between RAID controllers and Samsung Spinpoint F1...
over a year ago
4
over a year ago
There are some reports about incompatibility between RAID controllers and Samsung Spinpoint F1 drives. I have no troubles with my 0.5 and 1.0 TB drives from Samsung using mentioned controller. See below: Controller 1: RocketRAID 232x SATA Controller 1/1/1 SAMSUNG HD103UJ...
Louwrentius
Automated install of Debian Linux based on PXE net booting Every honest and good system administrator is continue bussy with automating his work. For two...
over a year ago
10
over a year ago
Every honest and good system administrator is continue bussy with automating his work. For two reasons: Repeating the same task over and over again is friggin boring. A system administrator has better things to do, such as drinking coffee. Humans make mistakes, especially if...
Louwrentius
FFmpeg performance on a Core i7 920 @ 3.6 Ghz The system i'm running is a Core i7 920 @ 3.6 Ghz. I am transcoding a DVD (Grave Of The Fire Flies)...
over a year ago
8
over a year ago
The system i'm running is a Core i7 920 @ 3.6 Ghz. I am transcoding a DVD (Grave Of The Fire Flies) to iPod format (640x480 x264). Thread support is enabled, to FFmpeg uses about 250% CPU. That's 2.5 of the 4 cores available. If possible, I would have liked to see it use all four...
Louwrentius
How to escape file names in bash shell scripts After fighting with Bash for quite some time, I found out that the following code provides a nice...
over a year ago
10
over a year ago
After fighting with Bash for quite some time, I found out that the following code provides a nice basis for escaping special characters. Ofcource it is not complete, but the most important characters are filtered. If anybody has a better solution, please let me know. It works and...
Louwrentius
Distributed Parallel Processing Shell Script (PPSS) released I'd like to announce the release of the distributed version of the Parallel Processing Shell Script...
over a year ago
9
over a year ago
I'd like to announce the release of the distributed version of the Parallel Processing Shell Script (PPSS). PPSS is a bash script that allows you to run commands in parallel. It is written to make use of current multi-core CPUs. The new distributed version of PPSS allows you to...
Louwrentius
Core i7 920 @ 3,6 Ghz is a true beast! Even today, Core 2 Duo processors clocked at 2 ghz are no slugs. However, the Core i7 920 is of a...
over a year ago
7
over a year ago
Even today, Core 2 Duo processors clocked at 2 ghz are no slugs. However, the Core i7 920 is of a different kind. First, it is not only clocked at a higher speed (default 2,8 Ghz), it is also a quad-core processor. Thanks to the re- introduction of hyperthreading, this processor...
Louwrentius
'Linux: unattended installation with Debian preseeding' Debian Linux provides a mechanism to install the operating system without user intervention. This...
over a year ago
6
over a year ago
Debian Linux provides a mechanism to install the operating system without user intervention. This mechanism is called 'preseeding' and is similar to Red Hat Kick Start and Sun Solaris Jump Start. The basic idea is that the installer is fed a recipe, according to which the system...
Louwrentius
Why Debian/Ubuntu Linux is to be preferred There are many Linux distributions around. However, I always come back to just one: Debian. The...
over a year ago
5
over a year ago
There are many Linux distributions around. However, I always come back to just one: Debian. The reason why so many people use Debian is the same reason I like it so much: software management.  With good old apt-get or the new aptitude, software is installed within minutes. Due to...
Louwrentius
Why I still won't switch to Linux and keep my Mac The current state of Linux is amazing. If we take a look at, for example, Ubuntu Linux, we have to...
over a year ago
4
over a year ago
The current state of Linux is amazing. If we take a look at, for example, Ubuntu Linux, we have to admit that the Linux desktop is really becoming a nice, user-friendly environment. I'm truly starting to like what I see. I considered whiping Mac OS X from my macbook, but there...
Louwrentius
Unattended automatic installation of Linux nvidia binary driver As part of an unattended installation, it was necessary to install a binary nvidia graphics driver....
over a year ago
6
over a year ago
As part of an unattended installation, it was necessary to install a binary nvidia graphics driver. This is a manual proces by default. However, it can be done fully automatic: prerequisite: install xserver-xorg-dev package or similar xorg development package. sh NVIDIA-.run -q...
Louwrentius
Release of PPSS - the Parallel Processing Shell Script PPSS is a shell script that processess files or other items in parallel. It is designed to make use...
over a year ago
7
over a year ago
PPSS is a shell script that processess files or other items in parallel. It is designed to make use of the current multi-core CPUs. It will detect the number of available CPUs and start a thread for each CPU core.  This script is build with the goal to be very easy to use. Also,...
Louwrentius
Benefits of hyper-threading on a Core 7i processor I had some wave files that I wanted to encode to mp3. I wrote a small parallel processing framework...
over a year ago
5
over a year ago
I had some wave files that I wanted to encode to mp3. I wrote a small parallel processing framework for this job. It executes parallel jobs so I can benefit from the 4 cores + 4 virtual cores of my new Core 7i 920 processor.  The framework is based on some shell scripts running...
Louwrentius
Rebooting results in degraded RAID array using Debian Lenny As described earlier, I setup a RAID 6 array consisting of physical 1 TB disk and 'virtual' 1 TB...
over a year ago
7
over a year ago
As described earlier, I setup a RAID 6 array consisting of physical 1 TB disk and 'virtual' 1 TB disks that are in fact two 0.5 TB disks in RAID 0.  I wanted to upgrade to Lenny because the new kernel that ships with Lenny supports growing a RAID 6 array. After installing Lenny...
Louwrentius
Calculating EXT2 EXT3 EXT4 stride size when using RAID When formatting a RAID device with an EXT filesystem, it is always advised to specify a stride size....
over a year ago
8
over a year ago
When formatting a RAID device with an EXT filesystem, it is always advised to specify a stride size. The format utility will take this stride size into account when formatting a device. The stride size is the number you get when you divide the 'chunck' size, as specified with...
Louwrentius
Did you know that RDP is as insecure as telnet? Microsoft developed the remote desktop protocol in order to allow remote GUI- based access to hosts....
over a year ago
8
over a year ago
Microsoft developed the remote desktop protocol in order to allow remote GUI- based access to hosts. It is easy to pick on Microsoft and I do respect what they have accomplished, however, it may not come as a surprise that they did it all wrong with RDP in terms of security. By...
Louwrentius
The kind of sound you never want to hear from your computer The sounds of hard drives that have perished These sounds are only frightening or scary if you...
over a year ago
8
over a year ago
The sounds of hard drives that have perished These sounds are only frightening or scary if you imagine your precious data only exists on that failing drive. If you make consistent and frequent backups and/or you run a fault-tolerant RAID flavour, it is but a nuisance.
Louwrentius
Is storage really that cheap? Nowadays you can buy a 1 TB harddrive for less than 100 euro's . So I build myself a 4 TB NAS box,...
over a year ago
10
over a year ago
Nowadays you can buy a 1 TB harddrive for less than 100 euro's . So I build myself a 4 TB NAS box, which is already 50% full. However, although it is to some degree fault-tollerant by using RAID 6, one mistake or catastrophic hardware faillure and all data is lost. And that's...
Louwrentius
Highpoint RocketRAID 2320 on Debian howto Get the 'open source' driver from www.highpoint-tech.com. (It's not open source, it uses a closed...
over a year ago
7
over a year ago
Get the 'open source' driver from www.highpoint-tech.com. (It's not open source, it uses a closed binary driver.) http://www.highpoint-tech.com/USA/bios_rr2320.htm Install the kernel headers if you haven't already - apt-get install linux-headers-2.6.18-6-k7 - extract the...
Louwrentius
Building a RAID 6 array of mixed drives To be honest, 4 TB of storage isn't really necessary for home usage. However, I like to collect...
over a year ago
9
over a year ago
To be honest, 4 TB of storage isn't really necessary for home usage. However, I like to collect movies in full DVD or HD quality and so I need some storage. I decided to build myself a NAS box based on Debian Etch. Samba is used to allow clients to access the data. The machine...