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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

https://github.com/zfsonlinux/zfs/wiki/RHEL-and-CentOS

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

raidz/raidz1 - one drive can fail (requires 3+ drives)
raidz2 - two drives can fail (requires 3+ drives)
raidz3 - three drives can fail (requires 4+ drives)

 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

 linux-headers-generic
 linux-image-generic
 zfsutils-linux

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