storage: ~ # zpool status
  pool: external1
 state: ONLINE
status: One or more devices has experienced an unrecoverable error.  An
        attempt was made to correct the error.  Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
        using 'zpool clear' or replace the device with 'zpool replace'.
   see: http://illumos.org/msg/ZFS-8000-9P
  scan: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        external1   ONLINE       0     0     0
          raidz2-0  ONLINE       0     0     0
            da2     ONLINE       0     0     0
            da0     ONLINE       0     0     0
            da1     ONLINE       3    19     0
            da3     ONLINE       0     0     0

errors: No known data errors