Category / ZFS

ZFS has this less documented feature, called share[nfs|smb]; I tried it once, it “did not work on first attempt”™ So I ignored it; However now we faced an issue where we normally exported ZFS volumes using /etc/exports (NFS); and mounted using /etc/fstab; but got an empty directory where there was a “sub” zpool volume; This […]

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Create ZFS Raidz2 pool

20 March, 2019

This is a quick howto, I made a raidz2 pool on ZFS, its very similar to how to create a mirror. find out what disks you are giving to the pool : [email protected]:~# fdisk -l /dev/sd* | grep Disk Disk /dev/sda: 9.1 TiB, 10000831348736 bytes, 19532873728 sectors Disk /dev/sdb: 9.1 TiB, 10000831348736 bytes, 19532873728 sectors […]

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Understanding ZFS : Checksum

6 February, 2019

Ever wondered what kind of checksum ZFS uses to check for bit rot ? Probably not, but it turns out you can change the used algorithm. However like most settings, the defaults are chosen by smart people. So changing it might not be doing you any favors. As it turns out, the default checksum used […]

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This is the tale of caution, when sleep deprived, sysadmin with caution! Let’s be honest who never said : lets finish this game, let’s have another drink, I will sleep when dead, … (enter sleepless night excuse here) ? Last night for me I was on a coding spree, when a thunderstorm broke, I was […]

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ZFS quota

19 April, 2017

ZFS is loaded with useful features, just a while ago I took a peak at setting quotes. Using just a few commands you limit the amount  of storage a certain pool can take. First let’s check if there is no quota set : zfs get quota This would result in something like : # zfs […]

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ZFS replace a broken disk

28 March, 2017

After a reboot, I got greeted with this error : [email protected]:~# zpool status pool: rpool state: DEGRADED status: One or more devices could not be used because the label is missing or invalid. Sufficient replicas exist for the pool to continue functioning in a degraded state. action: Replace the device using ‘zpool replace’. see: […]

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Create a ZFS mirror pool

8 March, 2017

I recently revived a “old” compute cluster. While its hardware was formidable back in the day, now it has been replaced with a younger version, which has more compute nodes. I wanted to create a data partition of two disks, normally I have a raid controller but on this server, there is none.  An open invitation for […]

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Install ZFS on Centos

17 February, 2017

Installing ZFS on Centos has been ironed out pretty much, so just follow along. There are three ways I know of to install ZFS on Centos. The two methods are recommended, as they use a repository, the last is just compiling from source, which I like, since I decide when its updated. (as kernel updates […]

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After the fairy dust has settled on Let’s Encrypt, allot of good solutions are out there to get a valid certificate using the ACME protocol (see client list). Most of the technique’s use webroot as verification technique, while this is fine for most websites, it has some downsides. For one, you need to adapt (let […]

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Tuning of ZFS module

31 January, 2017

Tuning of ZFS module The more difficult part of ZOL is the fact that there are plenty of tune able kernel module parameters, and hence ZFS can be used in many kinds of systems for many different reasons. (laptops, file-servers, database-servers, file-clusters) However some of the parameters come bad out of the box for file […]

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