MIGRATING
A disk is reported as MIGRATING after a DIAGNOSTIC disk is manually failed. After a disk is marked as MIGRATING, data migration begins. Data migration moves data from the MIGRATING disk to neighboring drives. This process reduces the amount of data that needs to be rebuilt when the disk is replaced. The disk is permanently removed after all data is migrated.
Note: During upgrade, disk migration aborts and does not resume when the upgrade
completes.