Originally Posted by raymor

With RAID0 (striping) performance is roughly doubled because you get the speed of both drives. The setup with three drives is called RAID3 or RAID5. Basically the third drive holds a checksum of the others, so if any single drive fails the data is still readable. We have RAID5 arrays of eight drives apiece. Reads can use all drives, so the more drives the faster files can be read. The capacity is that of seven drives, with one used for parity.

RAID3 has one drive dedicated to parity and is good for sequential access, like videos. It slow for random writes, though, because all writes have to update the one parity drive.

The more popular RAID5 has a few blocks on each drive used for parity and is good for random access, like the OS. It's fast for reading because reads use all drives, but slightly slower than RAID0 for writes because writes have to update two drives, not just one. The writes may be executed parallel, though, so it's not always half as fast as RAID0. RAID5 is good balance between safety, capacity, and speed in many cases because most systems read files more often than write them.

That reminds me, MrMaxwell there's something else I'd like to chat with you about. Can you shoot me an email at ray @ bettercgi.com or give me a call at 979-530-1300.