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.
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.
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.