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ZFS

ZFS Install

Ubuntu

On ubuntu based systems after 16.04 it’s enough to run

apt install zfsutils-linux

for zfs support to be installed.

Mint

The same as Ubuntu.

Centos7

Add module to autoload by creating file /etc/modules-load.d/zfs.conf with content

zfs

ZFS pools

Create a striped pool

zpool create -o ashift=12 -m <mountpoint> <pool-name> <device1> <device2>

Create a mirror pool

zpool create -o ashift=12 -m <mountpoint> <pool-name> mirror <device1> <device2>

Create a raidz pool

zpool create -o ashift=12 -m <mountpoint> <pool-name> raidz <device1> <device2> <device3>

Add device to pool

Please note you should match current pool type for accurate redundancy.

zpool add <pool-name> mirror|raidz(2,3)|none <device(s)>

Get status on pool

zpool status <pool-name>

Delete pool

zpool destroy <pool-name>

List pools

zpool list

Rename pool

This is a two step process. First the pool must be exported, then imported to a new name.

zpool export <pool-name>
zpool import <pool-name> <new-pool-name>

Import pool

Typically after re-installing the OS the datadrive (zfs) needs to be imported. Again this is a two step process.

zpool import

will list the zfs pools that it can find. Then it’s just a matter of running

zpool import -f <pool-name>

to import the pool and mount the datasets.

Make sure to use by-id or similar for import as device naming (sd*) can change.

zpool import -f -d /dev/disk/by-id <pool-name>

ZFS datasets

or filesystems, as some call them

Create dataset

zfs create -o mountpoint=<mountpoint> <pool-name>/<dataset>

Delete dataset

zfs destroy <pool-name>/<dataset>

Set Quota

zfs set quota=xxG <pool-name>/<dataset>

ZFS snapshots

Create a snapshot

zfs snapshot -r <pool-name>/<dataset>@<snapshot-name>

List snapshots

zfs list -t snapshot

Rollback to snapshot

zfs rollback <pool-name>/<dataset>@<snapshot-name>

Delete snapshot

zfs destroy <pool-name>/<dataset>@<snapshot-name>

Delete all snapshots

for snapshot in zfs list -H -t snapshot -r <pool>|cut -f 1; do zfs destroy $snapshot; done

Troubleshooting

Cannot load zfs module

ZFS installation problems on KDE Neon (16.04).

$ zpool status
The ZFS modules are not loaded.
Try running '/sbin/modprobe zfs' as root to load them.

$ /sbin/modprobe zfs
modprobe: ERROR: could not insert 'zfs': Unknown symbol in module, or unknown parameter      (see dmesg)

It seems there is a problem on a fresh install of KDE Neon (16.04) where the kernel installed is not the same as the kernel headers. My only solution was to remove all zfs and kernel related packages and reinstall the following packages