---| louwrentius.com
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 your …| Louwrentius
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 might not be an …| Louwrentius
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 the same …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 performance can be …| Louwrentius
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 work. Introduction By default, Ubuntu …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 power-efficient The …| Louwrentius
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 have absolutely zero relevant background …| Louwrentius
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 suspect to integrate RAIDZ …| Louwrentius
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 …| Louwrentius
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 Fossa' LTS, back in April 2020, Canonical decided that the new …| Louwrentius
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 decided to use an …| Louwrentius
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 these issues 'technical debt' seems …| Louwrentius
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) website. For …| Louwrentius
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 myth …| Louwrentius
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 that people tend to …| Louwrentius
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 …| Louwrentius
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 .json …| Louwrentius
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 …| Louwrentius
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 and run …| Louwrentius
Want to listen to this article? Your browser does not support the 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 cryptocurrencies in one simple …| Louwrentius
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. If you run your applications / workloads …| Louwrentius
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 obtained by connecting the SSDs to a …| Louwrentius
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 …| Louwrentius
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 that automates testing …| Louwrentius
I've bought a secondhand HP DL380p Gen8 server and I think it's awesome. This machine has dual-processors, with each CPU having 10 physical cores and two threads per core, for a grand total of 20 cores / 40 threads for the entire machine. It's also equiped with 128 GB or memory …| Louwrentius
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 components: 3 x Raspberry Pi …| Louwrentius
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
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 find …| Louwrentius
--- ⚠️ 🚨 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 article has been substantially updated since …| Louwrentius
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. Price In …| Louwrentius
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 downsides: you can only …| Louwrentius
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 virtual machines from backup and once …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 for ECC memory …| Louwrentius
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 …| Louwrentius
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 automate and …| Louwrentius
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 …| Louwrentius
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 not easy and I was …| Louwrentius
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 so, you will be …| Louwrentius
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 IP-address. It is called virtual because …| Louwrentius
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. FSS cryptographically …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 'configure' process and I killed it …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
--- 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 …| Louwrentius
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 …| Louwrentius
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
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 …| Louwrentius
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 file servers synchronised. Click here if or there you …| Louwrentius
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 environment …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 for protection of …| Louwrentius
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 interface with the …| Louwrentius
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 own NAS, are …| Louwrentius
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 …| Louwrentius
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 about $160 or €160, which …| Louwrentius
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 …| Louwrentius
--- 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 …| Louwrentius
I wrote a small Python script called 'showdisks' that displays relevant information about any physical storage devices supported by hdparm. | Louwrentius
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 the …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 Bressers: Putting a …| Louwrentius
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 is that projects are …| Louwrentius
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 different …| Louwrentius
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 …| Louwrentius
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
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 'professional GPUs' …| Louwrentius
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 …| Louwrentius
--- 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 created with GNUplot. The …| Louwrentius
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 ColdFusion as a platform for their …| Louwrentius
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 if …| Louwrentius
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 writes So what does this mean …| Louwrentius
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 environment, but worst-case, these tests show what …| Louwrentius
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
--- 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 speed of your car (unless you …| Louwrentius
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 …| Louwrentius
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, network links and RAID …| Louwrentius
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 handing over their …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 …| Louwrentius
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 content-scanning proxy server may provide you with one of these …| Louwrentius
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 …| Louwrentius
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 apply service …| Louwrentius
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 PCs. WDS can also be used …| Louwrentius
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 data store. It is not understood …| Louwrentius
My 4U 71 TiB ZFS NAS built with twenty-four 4 TB drives is over 10 years old and still going strong.| louwrentius.com
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 still hampered by SD card performance1. And the Pi isn't that cheap either.| louwrentius.com
Introduction| louwrentius.com