Hitachi HF-W2000 35 User Manual page 182

9. RAID1
9. If the RAID status shows "Optimal (Media Error)", it is reccommended that you back up
the data and replace the two HDDs with new HDDs. Refer the replacement procedure to
Subsection 5.4.3, "Detaching/attaching hard disk drive (HDD)".
After the replacement, set up the Equipment all over again according to Subsection 9.2.2,
"Procedure of new setup" and then restore the data from the backup file according to
Section 8.1 "Backing Up Files".
Alternatively, restore the Equipment by utilizing a backup HDD (see Subsection 9.5.2,
"Performing restoration from backup HDD").
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