Mirrored vdevs are great for performance and it is quite straight-forward to add a mirrored vdev to an existing pool (presumably one with one or more similar vdevs already):
zpool add [poolname] mirror [device01] [device02] [device03]
If it’s a two-way mirror you will only have two devices in the above. An example for ZFS on Ubuntu with a pool named seleucus and two SSDs could look like:
zpool add seleucus mirror ata-SAMSUNG_SSD_830_Series_S0XYNEAC705640 ata-M4-CT128M4SSD2_000000001221090B7BF9
As always, it’s good practice to use the device name found in /dev/disk/by-id/ rather than the sda, sdb, sdc etc. names as the latter can change – the former do not.
This is a question that crops up fairly regularly, as different operating systems support different zpool versions. Fortunately, it’s quite easy to find out which versions you are running – simply run:
# zpool upgrade
If you want a more detailed readout, including the features of the pool version you have, try:
# zpool upgrade -v
Your output should look something like this:
# zpool upgrade -v
This system is currently running ZFS pool version 28.
The following versions are supported:
VER DESCRIPTION
— ——————————————————–
1 Initial ZFS version
2 Ditto blocks (replicated metadata)
3 Hot spares and double parity RAID-Z
4 zpool history
5 Compression using the gzip algorithm
6 bootfs pool property
7 Separate intent log devices
8 Delegated administration
9 refquota and refreservation properties
10 Cache devices
11 Improved scrub performance
12 Snapshot properties
13 snapused property
14 passthrough-x aclinherit
15 user/group space accounting
16 stmf property support
17 Triple-parity RAID-Z
18 Snapshot user holds
19 Log device removal
20 Compression using zle (zero-length encoding)
21 Deduplication
22 Received properties
23 Slim ZIL
24 System attributes
25 Improved scrub stats
26 Improved snapshot deletion performance
27 Improved snapshot creation performance
28 Multiple vdev replacements
For more information on a particular version, including supported releases,
see the ZFS Administration Guide.
Or for the more simple command:
# zpool upgrade
This system is currently running ZFS pool version 28.
All pools are formatted using this version.
