Hitachi HF-W7500 65 Instruction Manual page 284

10. RAID1
<NOTE>
・If the RAID status is shown as [Optimal(Media Error)] after rebuilding has been
completed, we recommend that you back up data and then also replace the copy
source drive with a new one. (For the replacement procedure, see "6.3.6
Installing and removing an HDD or SSD".)
After both drives have been replaced, set up the equipment again and restore
data from the backup file. (For how to set up the equipment again, see "10.2.2
Setting Up a New RAID1".) Or, recover the equipment by using the backup drive.
(See "10.5.2 Recovery Using a Backup Drive".)
Hardware Status Window (Media Error)
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