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Replacing disks that are currently being used in an aggregate

You can use the disk replace command to replace disks that are part of an aggregate without disrupting data service. You do this to swap out mismatched disks from a RAID group. Keeping your RAID groups homogeneous helps optimize storage system performance.

Before you begin

You should already have an appropriate hot spare disk of the correct type, size, speed, and checksum type installed in your storage system. This spare disk must be assigned to the same system and pool as the disk it will replace. For multi-disk carrier disks, you should have at least two hot spare disks available, to enable Data ONTAP to provide an optimal disk layout.

About this task

If you need to replace a disk—for example a mismatched data disk in a RAID group—you can replace the disk. This operation uses Rapid RAID Recovery to copy data from the specified old disk in a RAID group to the specified spare disk in the storage system. At the end of the process, the spare disk replaces the old disk as the new data disk, and the old disk becomes a spare disk in the storage system.
Note: If you replace a smaller disk with a larger disk, the capacity of the larger disk is downsized to match that of the smaller disk; the usable capacity of the aggregate is not increased.


  1. Enter the following command: disk replace start [-m] old_disk_name new_spare_disk_name

    If you need to use a disk that does not match the speed or pool of the other disks in the aggregate, you can use the -m option.

    If you need to stop the disk replace operation, you can use the disk replace stop command. If you halt a disk replace operation, the target spare disk needs to be zeroed before it can be used in another aggregate.


The old disk is converted to a spare disk, and the new disk is now used in the aggregate.