Use the Pre-read Redundancy Check option to define a capability to pre-read information and determine whether the data of that logical drive is consistent. A logical drive that has this feature enabled returns read errors if the data is determined to be inconsistent by the controller firmware. You can enable this option for logical drives that contain redundancy information. RAID Level 1, RAID Level 3, RAID Level 5, and RAID Level 6 maintain redundancy information. You can enable redundancy pre-read on a per-logical drive basis. You can enable this check for normal logical drives, flashcopy base logical drives, and flashcopy repository logical drives.
If a logical drive that is configured with pre-read is migrated to a RAID level that does not maintain redundancy information, the metadata of the logical drive will continue to show that pre-read is enabled. However, reads to that logical drive will ignore redundancy pre-read. If the logical drive is subsequently migrated back to a RAID level that supports redundancy, the option will become available again.
Note:
Enabling the option on logical drives without redundancy does not affect the logical drive. However, the attribute is retained for that logical drive if it is ever changed to one with redundancy information.You can view whether Pre-read redundancy check is enabled by accessing the Logical Drive Properties window or the Storage Subsystem Profile window.