Replacing a Device in a ZFS Storage Pool (Solaris ZFS Administration Guide)

Solaris ZFS Administration Guide

Replacing a Device in a ZFS Storage Pool

Once you have determined that a device can be replaced, use the zpool replace command to replace the device. If you are replacing the damaged device with another different device, use the following command:

# zpool replace tank c1t1d0 c2t0d0

This command begins migrating data to the new device from the damaged device, or other devices in the pool if it is in a redundant configuration. When the command is finished, it detaches the damaged device from the configuration, at which point the device can be removed from the system. If you have already removed the device and replaced it with a new device in the same location, use the single device form of the command. For example:

# zpool replace tank c1t1d0

This command takes an unformatted disk, formats it appropriately, and then begins resilvering data from the rest of the configuration.

For more information about the zpool replace command, see Replacing Devices in a Storage Pool.

Example 11–1 Replacing a Device in a ZFS Storage Pool

The following example shows how to replace a device (c1t3d0) in the mirrored storage pool tank on a Sun Fire x4500 system. If you are going to replace the disk c1t3d0 with a new disk at the same location (c1t3d0), then unconfigure the disk before you attempt to replace it. The basic steps are as follows:

Offline the disk to be replaced first. You cannot unconfigure a disk that is currently being used.
Identify the disk (c1t3d0) to be unconfigured and unconfigure it. The pool will be degraded with the disk offlined in this mirrored configuration but the pool will continue to be available.
Physically replace the disk (c1t3d0). Make sure that the blue "Ready to Remove" LED is illuminated before you physically remove the faulted drive.
Reconfigure the disk (c1t3d0).
Bring the disk (c1t3d0) back online.
Run the zpool replace command to replace the disk (c1t3d0).

Note –
If you had previously set the pool property autoreplace=on, then any new device, found in the same physical location as a device that previously belonged to the pool, is automatically formatted and replaced without using the zpool replace command. This feature might not be supported on all hardware.
If a failed disk is automatically replaced with a hot spare, you might need to detach the hot spare after the failed disk is replaced. For example, if c2t4d0 is still an active spare after the failed disk is replaced, then detach it.
# zpool detach tank c2t4d0

# zpool offline tank c1t3d0
# cfgadm | grep c1t3d0
sata1/3::dsk/c1t3d0            disk         connected    configured   ok
# cfgadm -c unconfigure sata1/3
Unconfigure the device at: /devices/pci@0,0/pci1022,7458@2/pci11ab,11ab@1:3
This operation will suspend activity on the SATA device
Continue (yes/no)? yes
# cfgadm | grep sata1/3
sata1/3                        disk         connected    unconfigured ok
<Replace the physical disk c1t3d0>
# cfgadm -c configure sata1/3
# cfgadm | grep sata1/3
sata1/3::dsk/c1t3d0            disk         connected    configured   ok
# zpool online tank c1t3d0
# zpool replace tank c1t3d0
# zpool status
  pool: tank
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Tue Apr 22 14:44:46 2008
config:

        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          mirror    ONLINE       0     0     0
            c0t1d0  ONLINE       0     0     0
            c1t1d0  ONLINE       0     0     0
          mirror    ONLINE       0     0     0
            c0t2d0  ONLINE       0     0     0
            c1t2d0  ONLINE       0     0     0
          mirror    ONLINE       0     0     0
            c0t3d0  ONLINE       0     0     0
            c1t3d0  ONLINE       0     0     0

errors: No known data errors

Note that the preceding zpool output might show both the new and old disks under a replacing heading. For example:

replacing     DEGRADED     0     0    0
  c1t3d0s0/o  FAULTED      0     0    0
  c1t3d0      ONLINE       0     0    0

This text means that the replacement process is in progress and the new disk is being resilvered.

If you are going to replace a disk (c1t3d0) with another disk (c4t3d0), then you only need to run the zpool replace command. For example:

# zpool replace tank c1t3d0 c4t3d0
# zpool status
  pool: tank
 state: DEGRADED
 scrub: resilver completed after 0h0m with 0 errors on Tue Apr 22 14:54:50 2008
config:

        NAME           STATE     READ WRITE CKSUM
        tank           DEGRADED     0     0     0
          mirror       ONLINE       0     0     0
            c0t1d0     ONLINE       0     0     0
            c1t1d0     ONLINE       0     0     0
          mirror       ONLINE       0     0     0
            c0t2d0     ONLINE       0     0     0
            c1t2d0     ONLINE       0     0     0
          mirror       DEGRADED     0     0     0
            c0t3d0     ONLINE       0     0     0
            replacing  DEGRADED     0     0     0
              c1t3d0   OFFLINE      0     0     0
              c4t3d0   ONLINE       0     0     0

errors: No known data errors

You might have to run the zpool status command several times until the disk replacement is complete.

# zpool status tank
  pool: tank
 state: ONLINE
 scrub: resilver completed after 0h0m with 0 errors on Tue Apr 22 14:54:50 2008
config:

        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          mirror    ONLINE       0     0     0
            c0t1d0  ONLINE       0     0     0
            c1t1d0  ONLINE       0     0     0
          mirror    ONLINE       0     0     0
            c0t2d0  ONLINE       0     0     0
            c1t2d0  ONLINE       0     0     0
          mirror    ONLINE       0     0     0
            c0t3d0  ONLINE       0     0     0
            c4t3d0  ONLINE       0     0     0

Example 11–2 Replacing a Failed Log Device

The following example shows to recover from a failed log device c0t5d0 in the storage pool, pool. The basic steps are as follows:

Review the zpool status -x output and FMA diagnostic message, described here:

http://www.sun.com/msg/ZFS-8000-K4
Physically replace the failed log device.
Bring the log device online.
Clear the pool's error condition.

# zpool status -x
  pool: pool
 state: FAULTED
status: One or more of the intent logs could not be read.
        Waiting for adminstrator intervention to fix the faulted pool.
action: Either restore the affected device(s) and run 'zpool online',
        or ignore the intent log records by running 'zpool clear'.
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        pool        FAULTED      0     0     0 bad intent log
          mirror    ONLINE       0     0     0
            c0t1d0  ONLINE       0     0     0
            c0t4d0  ONLINE       0     0     0
        logs        FAULTED      0     0     0 bad intent log
          c0t5d0    UNAVAIL      0     0     0 cannot open
<Physically replace the failed log device>
# zpool online pool c0t5d0
# zpool clear pool