A physical drive is marked failed when there is a loss of communication between the controller and the physical drive. This can be caused by any of the following:
In each case, after the communication problem is resolved, a rebuild operation is required to reconstruct the data for the device in its disk disk group. The controllers can reconstruct RAID level-1, level-5, level-10, and level-50 logical devices. They cannot, however, reconstruct data stored in RAID level-0 logical devices because RAID level-0 is not redundant. If a disk group contains only RAID level-0 logical drives, the logical devices in the disk group are marked failed and the logical devices contain damaged data. You cannot rebuild the logical devices. You must correct the cause of the failure or replace the physical drives; then, you must restore your data.
To prevent data-integrity problems, the controllers set the RAID level-0 logical devices in the affected disk group to blocked during the rebuild operation for RAID level-1 or RAID level-5. After the rebuild operation is completed, you can unblock the RAID level-0 logical devices and access them once again. Remember, however, that the RAID level-0 logical devices contain damaged data.
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