I have a pool of four raidz1 on Solaris 10, three of which look like this:

state: ONLINE
status: One or more devices is currently being resilvered.  The pool will
        continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
 scan: resilver in progress since Wed Jun 17 16:46:31 2015
    536G scanned out of 43.9T at 389M/s, 32h26m to go
    536G scanned out of 43.9T at 389M/s, 32h26m to go
    27.3G resilvered, 1.19% done

        NAME                                       STATE     READ WRITE CKSUM
        volume                                     ONLINE       0     0     0
          raidz1-0                                 ONLINE       0     0     0
            c0t600C0FF00012FBB109A2154F01000000d0  ONLINE       0     0     0
            c0t600C0FF00012FBB115A2154F01000000d0  ONLINE       0     0     0
            c0t600C0FF00012FBB139A2154F01000000d0  ONLINE       0     0     0
            c0t600C0FF00012FC7DFCA1154F01000000d0  ONLINE       0     0     0
            c0t600C0FF00012FBB151A2154F01000000d0  ONLINE       0     0     0
            c0t600C0FF00012FBB1E630025201000000d0  ONLINE       0     0     0  (resilvering)
            c0t600C0FF00012FBB169A2154F01000000d0  ONLINE       0     0     0
      c0t600C0FF00012FBB11555EC5401000000d0    AVAIL   

What does it mean if I see that resilvering kicked in although no disk is marked OFFLINE or UNAVAIL? Is it safe to remove one of the disks from the array? Should I replace the resilvering device by a spare?

1 Answer 1


There are a couple of explanations. One of them is that the system lost contact to the disk for a while and is now updating the latest changes to that disk.

You should not remove a disk while it is resilvering, because RAIDz1 has only a single disk fault tolerance.

  • zpool history or zdb will show you exactly why resilvering was triggered but yes, it just means all disks are online but at some point in the past an error occurred on one of them.
    – noitsbecky
    Jun 18, 2015 at 15:42

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