Posted by: Anonymous
on January 21, 2008 09:25 PM
--- Truth told, Linux (mdm native, not FakeRAID) softRAID actually offers better read performance then most hardware RAIDs cards. The reason being is that Linux natively multi-threads and does a split reads when possible (reads from both/all disks simultaneously). It (sadly) appears that many hardware RAIDs fail this test (including 3ware 9xxx series based on my testing). If you want a hardware RAID solution that does manage multi disk reads consider the Areka models.
--- RAID 5 should actually be lower performance than RAIDs 1/0. The reason is the overhead of calculating parity bits. It is not unusual for Hardware RAID5 to perform on par with a single disk write. The hardware CPU unit spends it's extra time in parity. If you are going to RAID5 in software, go with a multi-core CPU configuration.
--- Of course if you want ultimate performance (price be damned) pair an Areka with Mtron SSD units. Using 5 64G Mtrons in RAID5 we attained over 400Mb/sec write performance and about 450 Mb/sec reads.