To access the data that was contained on a failed disk unit, device parity
protection must read each disk unit in the device parity set that contains
the failed disk unit. Because the read operations can be overlapped, the performance
affect may be small.
Because a failed disk unit with device parity protection may contain only
a small portion of user data, it is possible that only a few users will be
affected by the decrease in performance.
Note: RAID 6 operations
are derived from RAID 5, but at a further level of complexity. Because the
concept is similar to RAID 5, RAID 6 operations are not described here.