Noobie error: meant to setup Hot Spare but expanded the pool by mistake

[Fleshmauler]

It is too late now, but this might be relevant in the future:

ZFS Pool "Checkpoints": They work just like seatbelts! (Not really)

What is a ZFS Pool “Checkpoint”? [murphys-law] [murphys-law-with-a-net] If you do destructive or experimental actions against files and folders within a filesystem, you can always resort to rolling back to a dataset’s snapshot. Even if you don’t wish to do a full rollback (which will ultimately lose any new data after the point-in-time of the snapshot), you can still retrieve old or deleted files from the read-only filesystem (i.e, "snapshot) on an individual basis. But what safeguard exi…

Having a checkpoint set up (if I’m not mistaken) is the only way I can think of reverting a pool expansion without starting over from scratch.