If you have a global hot spare (GHS) drive when one of the active hard drives failes, your data is reconstructed to a GHS. Then, when you replace the failed drive, storage system automatically initiates a copyback, which gets the data from the GHS back to the replacement drive. Sometimes it doesn’t happen and replacement drive stays in an Unassigned state. If it is the case go to the DS Storage Manager, right click on the RAID array and select Replace Drives. There you should see the failed drive. Choose replacement from unassigned drives and click Replace Drive. Copyback will start immediately.
Take into consideration that copyback can be long-lasting, depending on the array size. If it is a production system and its performance is critical, right click on the logical drive, choose Change -> Modification Priority. There you can set how much resources will be allocated for modification (such as copyback, reconstruction, etc) and performance. Change it to Low for maximum performance.
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