Getting Started with ZFS in Ubuntu 20.04

ZFS in Ubuntu 20.04

I upgraded one of the smallest servers at home office to Ubuntu 20.04 recently and realised that ZFS support has been added to Ubuntu for quite some time - so maybe I should explore it more. I actually quite miss ZFS from my Sun Microsystems days.

Loading ZFS modules in Linux

Most likely you don’t have the ZFS modules loaded by default:

greys@server:~ $ lsmod | grep zfs

… meaning you need to probe ZFS modules to activate this functionality:

greys@server:~ $ sudo modprobe zfs

As you can see, there’s quite a few modules are loaded now:

greys@server:~ $ lsmod | grep zfs
zfs 4030464 0
zunicode 331776 1 zfs
zavl 16384 1 zfs
icp 286720 1 zfs
zcommon 90112 2 zfs,icp
znvpair 81920 2 zfs,zcommon
spl 126976 5 zfs,icp,znvpair,zcommon,zavl
zlua 147456 1 zfs

Installing ZFS utils in Ubuntu

Alright, next step is installing tools that provide all these z-commands for managing ZFS:

# apt-get install zfsutils

Creating ZFS pool from virtual disks

First, I’ll need a few virtual disks:

# fallocate -l 512M /vdisks/disk1.img

# fallocate -l 512M /vdisks/disk2.img

# fallocate -l 512M /vdisks/disk3.img

# fallocate -l 512M /vdisks/disk4.img

Nice! Now let’s create a ZFS pool (it’s like a RAID array if you’re familiar with mdadm):

zpool create -f newvol raidz /vdisks/disk1.img /vdisks/disk2.img /vdisks/disk3.img /vdisks/disk4.img

Confirm ZFS pool status in Ubuntu

Show ZFS pools: zpool list

Here it is: my newly created ZFS pool called newvol:

# zpool list

NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
newvol 1.88G 212K 1.87G - - 0% 0% 1.00x ONLINE -

Show ZFS pool status and member disks

Let’s get a bit more information about the pool - for instance, confirm which disks are in it:

# zpool status

pool: newvol
state: ONLINE
scan: none requested
config:

    NAME                   STATE     READ WRITE CKSUM
    newvol                 ONLINE       0     0     0
      raidz1-0             ONLINE       0     0     0
        /vdisks/disk1.img  ONLINE       0     0     0
        /vdisks/disk2.img  ONLINE       0     0     0
        /vdisks/disk3.img  ONLINE       0     0     0
        /vdisks/disk4.img  ONLINE       0     0     0

errors: No known data errors

I’m quite happy! Will be cool to use ZFS and snapshots for home directory on this box.

See Also

• Ubuntu 20.04
• Solaris blog
• Upgrading to Ubuntu 20.04