[oi-dev] Expanding raidzN vdevs?

[Reginald Beardsley]

If the capacity of the existing pool is small enough, buy 2 large drives, each capable of holding the pool with the space you want to add to the existing pool left over.  Partition the new drives, form a mirror on the big slices, transfer the data, then rebuild the  pool using the 6 drives plus the small slices on the new drives. Then use the large slices as a mirrored scratch space.  Or add 2 drives to match the other 6 and keep the big drives as universal spares.  In light of the restore time of large filesystems there is a strong business case for having a some disks on hand which are as large or larger than any disks in use which can be immediately installed to start the recovery.  If a drive failure was the result of an external event such as a lightening strike, you may have a rather short window before other drives fail.