J

Jeroen Louwrens

louwrentius.com · Personal blog · on HN since 2012

Jeroen Louwrens writes about home NAS builds, ZFS and other file systems, Ceph storage, and small-scale self-hosted hardware.

What HN saysHis ZFS and ECC memory post is cited in debates about ECC. Commenters also question his site's power use and his crypto views.
31HN people shared it
17linked it in comments
78stories submitted
2.5Kstory points
3 months agolast shared
2012people per year2026

Most-shared posts

  1. 1
    Please Use ZFS with ECC Memory (2014)
    12 people · 64 points · first shared 2014 · 106 comments on HN
  2. 2
    The 'hidden' cost of using ZFS for your home NAS
    4 people · 88 points · first shared 2016 · 83 comments on HN
  3. 3
    The Sorry State of CoW File Systems
    3 people · 130 points · first shared 2015 · 69 comments on HN
  4. 4
    The Raspberry Pi 5 Is No Match for a Tini-Mini-Micro PC
    2 people · 462 points · first shared 2024 · 351 comments on HN
  5. 5
    71 TiB DIY NAS Based on ZFS on Linux
    2 people · 165 points · first shared 2014 · 129 comments on HN
  6. 6
  7. 7
    Most Technical Debt Is Just Bullshit
    2 people · 42 points · first shared 2020 · 41 comments on HN
  8. 8
    Understanding Ceph: Open-Source Scalable Storage
    2 people · 9 points · first shared 2018 · discussion on HN
  9. 9
  10. 10
    Should I Use ZFS for My Home NAS?
    2 people · 2 points · first shared 2016 · discussion on HN
  11. 11
  12. 12
    My 71 TiB ZFS NAS After 10 Years and Zero Drive Failures
    1 people · 419 points · first shared 2024 · 299 comments on HN
  13. 13
  14. 14
    This Blog Is Now Running on Solar Power
    1 people · 228 points · first shared 2020 · 120 comments on HN
  15. 15
    An ode to the 10,000 RPM Western Digital (Veloci)Raptor
    1 people · 121 points · first shared 2021 · 111 comments on HN

What HN people wrote when they linked it

yreg · 2023-05-15
Obviously depends, but solar powered website currently uses 2.8W. [0] Louwrentius uses 29W? Do I read it correctly? [1] [0] https://solar.lowtechmagazine.com/power.html [1] https://louwrentius.com/
wting · 2020-11-19
>ECC is recommended but many people, myself included, have run many stable years without ECC. zfs requires ECC[0][1], do not skimp on this. I ran many zfs pools for >8 years without issues until silent memory corruption happened to me, and now I can't access my data anymore (zfs won't let me mount a zpool that fails scrub checks). 0: Oracle (and previously Sun) documentation recommends ECC to prevent silent corruption: >Consider using ECC memory to protect against memory corruption. Silent memory corruption can potentially damage your data. https://docs.oracle.com/cd/E23824_01/html/821-1448/zfspools-4.html 1: https://louwrentius.com/please-use-zfs-with-ecc-memory.html
louwrentius · 2020-09-12
I don't see any real purpuse for cryptocurrencies that benefits the greater good, to be frank. https://louwrentius.com/cryptocurrencies-are-detrimental-to-society.ht… I wish that smart people involved with this kind of technology would spend their time on something more relevant / important.
haunter · 2025-01-09
I'm in Hungary and for the equivalent of $120 you can get an enterprise refurbished mini PC (Dell, HP, Lenovo) with a much better CPU (i3-8100T, i5-8500T, i3-10100T for example) and storage options here. I'm running Dell Optiplex Micros with triple SSDs (1x 2.5", 2x NVMe). And it's x86 so you can prety much run whatever OS you want without any problems. The power consumption is perfectly fine too. Mines usually idle around 4-5W. Good article about the same topic https://louwrentius.com/the-raspberry-pi-5-is-no-match-for-a-tini-mini… Even a 10 years old i5-6500 is outperforming the RPI5!
TheHappyOddish · 2022-12-21
I think you're referring to ZFS specifically, and how it handles bit flips[1]. A NAS is an abstracted away concept from the OS or FS, so the type of memory isn't broadly relevant. 1. https://louwrentius.com/please-use-zfs-with-ecc-memory.html
belter · 2022-10-16
It looks like ZFS should be run with ECC "...We further demonstrate that ZFS is less resilient to memory corruption, which can lead to corrupt data being returned to applications or system crashes..." - https://research.cs.wisc.edu/wind/Publications/zfs-corruption-fast10.p… "Please Use ZFS With ECC Memory" - https://louwrentius.com/please-use-zfs-with-ecc-memory.html
magicalhippo · 2021-01-16
> All of the places I've seen, downloaded debs either write Debian 9+ or Debian 9+ Just a couple of recent examples I stumbled upon: https://www.armbian.com/nanopi-r2s/#kernels-archive-all https://louwrentius.com/configuring-scst-iscsi-target-on-debian-linux-… Sure a bit of searching lets me figure out what's what but...
jcastro · 2020-11-20
This is what I did, I just snagged some cheap Rosewill case off of newegg with 12 bays, a PCIe sata card and packed the case with drives. You can slice and dice the drives however you like. I found this guy's blog posts to be useful for running a homegrown NAS: - https://louwrentius.com/should-i-use-zfs-for-my-home-nas.html - https://louwrentius.com/the-hidden-cost-of-using-zfs-for-your-home-nas…
gulikoza · 2017-07-12
There's ton of sites when you google ashift=12, http://louwrentius.com/zfs-performance-and-capacity-impact-of-ashift9-… or https://github.com/zfsonlinux/zfs/issues/548 for instance. Basically, ashift=12 increases ZFS block size to 4K. Metadata use full blocks that would be 512b on ashift=9 but are now 4K (due to ashift=12). It wastes at least 3.5Kb more than normal 512 byte blocks for each block that is not filled entirely.
3legcat · 2017-03-13
> ECC is nice to have. Actually it seems ECC is important for ZFS filesystems see: http://louwrentius.com/please-use-zfs-with-ecc-memory.html
bespoke_engnr · 2016-01-03
Aside from the "needs many gigs of RAM, even without deduplication turned on" angle, the lack of ECC memory would prevent me from using ZFS on raspi. Sooner or later you will trash your data unless you're using ECC memory (which the Raspberry Pi RAM chips are not): http://louwrentius.com/please-use-zfs-with-ecc-memory.html For the record, I also think it's cool to get this compiled and running on RasPi; just wanted to add the ECC info for anyone now thinking of doing something with this in production :-D.
laymil · 2014-11-04
It's a rather fair statement to make. The rates of errors in memory are significant[1], and ZFS does nothing to ensure that in memory data structures are uncorrupted; it was designed to be used with ECC RAM[2]. [1]http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf [2]http://louwrentius.com/please-use-zfs-with-ecc-memory.html
moe · 2014-10-10
This is a myth started by someone who did not understand how filesystems work. You are wrong. Don't spread potentially dangerous maladvice on the internet when you have no idea what you're talking about. The official ZFS documentation[1] tells you to use ECC Ram and why. The first google hit for "zfs ecc ram"[2] further elaborates on the risks of using ZFS without ECC memory. [1] https://pthree.org/2013/12/10/zfs-administration-appendix-c-why-you-sh… [2] http://louwrentius.com/please-use-zfs-with-ecc-memory.html
Thaxll · 2014-09-09
Yes it does or I don't understand that: http://louwrentius.com/please-use-zfs-with-ecc-memory.html https://pthree.org/2013/12/10/zfs-administration-appendix-c-why-you-sh… Always fun to post on HN and getting downvoted ;o
ansible · 2019-12-20
> I don't care about ECC https://blog.codinghorror.com/to-ecc-or-not-to-ecc/ And that's fine. Though as a counterpoint: https://louwrentius.com/please-use-zfs-with-ecc-memory.html > I had hardware raid 5 before and it failed, because I used similar hard drives ( 3 drives failed within a month, wasn't expecting that). Which goes back to my point. You're comparing your home system, with something like one-9's uptime (90% availability over an entire year) with a cloud provider that is going to give you five-9's or better. These are not the same things. And you are going to pay more for each additional 9 of uptime. For your own stuff, yes, of course it can make perfect sense to host it yourself. I've got a personal server running on positively ancient hardware that still manages two-9's availability, and that's fine for my use case. But I wouldn't directly compare that to a cloud provider either.
dspillett · 2018-05-23
> upload of say ~20MB it would throttle my download speed This is not directly due to the technology involved, it is due to congestion on the upstream side slowing down IP control packets (ACKs and such) as they are queued with the rest. When you have a slow upstream pipe it is very easy to see this effect. It is even worse when there are multiple upstream connections trying to use as much as they can (as seen in torrent transfers and similar), and it affects interactive traffic like SSH connections significantly too. You can work around this by shaping your upstream traffic to reserve a little bandwidth for small interactive/control packets. If your router runs Linux there are a number of simple scripts to setup the basics (wondershaper is one I've used successfully in the past) or you can be more specific to your needs by setting up your own config with the appropriate tools. If you usually only use one PC then you can run the shaper there instead, of course, but running shaping on one individual machine on a crowded network will have no useful effect. (see http://louwrentius.com/how-traffic-shaping-can-dramatically-improve-in… for an example of using wondershaper)

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