Raid 5 vs. RAID 0+1

[Elfear]

I'm setting up a file server and trying to decide whether to use RAID 5 or 0+1. I have 4 250GB Sata II drives and I was thinking about using 3 in a RAID 5 and save the last as a cold spare. Will I notice a decrease in bandwidth using RAID 5 vs. 0+1? The server specs are as follows:

MSI Neo4 Platinum board with built in Silicon Image RAID chip (I believe it uses software based RAID 5)
Dual channel ram 2x512MB (not sure if that makes a difference)
Server will be set up on a gig network. I'm hoping this will be the limiting factor in bandwidth capabilities.

Thanks for any advice.

 

[imported_Kensai]

4 drives are better for RAID 5.

 

[Elfear]

If I used four drives would I get ~ the same bandwidth as a 0+1 array?

 

[ViRGE]

Originally posted by: Elfear
If I used four drives would I get ~ the same bandwidth as a 0+1 array?

Reading, probably. Writing however is flakier; the XOR ops needed for parity information will slow things down, especially on cheaper RAID cards. Without good benchmarks, I would guess that writing will be slower for a 3/4 driver RAID 5 than 0+1