Removed drive from a pool for testing. Pool shows as degraded. When you reinsert the drive, pool continues to show as degraded. Running zpool status results in:
jeffnas05# zpool status tank
status: One or more devices could not be used because the label is missing or
invalid. Sufficient replicas exist for the pool to continue
functioning in a degraded state.
action: Replace the device using 'zpool replace'.
NAME STATE READ WRITE CKSUM
tank DEGRADED 0 0 0
mirror-0 DEGRADED 0 0 0
bb405d46-5418-4699-94b2-855d13e4ed28 ONLINE 0 0 0
41f5df38-e9ca-4f6c-a7a1-d5d4b0d32df7 UNAVAIL 3 159 0
errors: No known data errors
The only way available that I have found to clear this and make the pool healthy after drive reinsertion is 'zpool clear tank'