Which version of ZFS allows shrinking of a pool?
Solution 1:
No current release can shrink a pool and I have not heard any announcements of an upcoming feature to do so. Considering how rare it is that a properly designed pool would need the ability, I wouldn't expect it anytime soon.
Solution 2:
The new ZFS version in Solaris 11.4 allows shrinkage of arrays. Say you have 5-disk array, you can now shrink to 4-disk array.
And, dedup has been fixed! It is using Greenbyte superior deduplication.
Solution 3:
I cant find that it is supported, yet anyways.
Here's a printout from my Solaris 11 Express running ZFS pool version 31.
zpool upgrade -v
This system is currently running ZFS pool version 31.
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
29 RAID-Z/mirror hybrid allocator
30 Encryption
31 Improved 'zfs list' performance
For more information on a particular version, including supported releases,
see the ZFS Administration Guide.