Spare State of dRAID pool does not become AVAIL after pool resilver has finished

[drearycold]

System information

Type	Version/Name
Distribution Name	Gentoo
Distribution Version	N/A
Kernel Version	5.10.76-gentoo-r1
Architecture	x86_64
OpenZFS Version	zfs-2.1.2-r1-gentoo zfs-kmod-2.1.2-r0-gentoo

Describe the problem you're observing

I've built a dRAID pool with specs draid1:4d:6c:1s. There was some interim problems with one of the disks, so spare have taken its place.
Since I know the disk is OK, I called zpool clear to reset the error counts. After reboot and resilver, zpool status shows that the state of spares is INUSE, which to my understanding should be AVAIL? Is this the right state? Or do I need to do something else?
Thanks for any help. I'm quite new to ZFS maintenance.

Describe how to reproduce the problem

Let one disk make some read/write error, clear the error, wait for resilver to complete.

Include any warning/errors/backtraces from the system logs

# zpool status
  pool: tank
 state: ONLINE
  scan: resilvered 1.27T in 08:45:06 with 0 errors on Wed Dec 22 19:44:15 2021
config:

        NAME                          STATE     READ WRITE CKSUM
        tank                          ONLINE       0     0     0
          draid1:4d:6c:1s-0           ONLINE       0     0     0
            scsi-350014e0eae48b89d    ONLINE       0     0     0
            scsi-350014e2e603e658d    ONLINE       0     0     0
            scsi-350014e2e603eb8ad    ONLINE       0     0     0
            scsi-350014e2e611923f9    ONLINE       0     0     0
            spare-4                   ONLINE       0     0     0
              scsi-350014e2e61248b68  ONLINE       0     0     0
              draid1-0-0              ONLINE       0     0     0
            scsi-350014e6e598d9392    ONLINE       0     0     0
        spares
          draid1-0-0                  INUSE     currently in use

errors: No known data errors

[behlendorf]

Good question. Because the virtual draid1-0-0 spare vdev is still included in the pool config you should expect the status to be INUSE.

        NAME                          STATE     READ WRITE CKSUM
        tank                          ONLINE       0     0     0
          draid1:4d:6c:1s-0           ONLINE       0     0     0
            scsi-350014e0eae48b89d    ONLINE       0     0     0
            scsi-350014e2e603e658d    ONLINE       0     0     0
            scsi-350014e2e603eb8ad    ONLINE       0     0     0
            scsi-350014e2e611923f9    ONLINE       0     0     0
            spare-4                   ONLINE       0     0     0
              scsi-350014e2e61248b68  ONLINE       0     0     0
>>>           draid1-0-0              ONLINE       0     0     0
            scsi-350014e6e598d9392    ONLINE       0     0     0
        spares
          draid1-0-0                  INUSE     currently in use

In order to return the spare the the AVAIL state you will need to run zpool detach tank draid1-0-0. This would normally happen automatically after the failed drive was replaced and it had finished rebuilding back. In your case, it's left the pool in the safest state until an administrator can determine the best course of action (i.e. perhaps that drive really is on its last legs and needs to go).

[drearycold]

Thanks!
zpool detach restored spare state to AVAIL.