RAID 3, Continued
RAID 5 vs RAID 3 You may find that RAID 5 is preferable to RAID 3, even for applications characterized by sequential reads and writes, because MegaRAID Express 500 has very robust caching algorithms.
The benefits of RAID 3 disappear if there are many small I/O operations scattered randomly and widely across the disks in the logical drive. The RAID 3 fixed parity disk becomes a bottleneck in such applications. For example: The host attempts to make two small writes and the writes are widely scattered, involving two different stripes and different disk drives. Ideally both writes should take place at the same time. But this is not possible in RAID 3, since the writes must take turns accessing the fixed parity drive. For this reason, RAID 5 is the clear choice in this scenario.
22MegaRAID Express 500 Hardware Guide