I've got a total of 8 physical disks I can use (not including 2 for the mirrored OS) for a fairly high-use SQL Server.

It's used to serve a web-app (Win2k3, IIS6, ASP.Net) which has fairly heavy usage (400K users) with a fairly even proportion of writing and reading. However the database isn't very large (yet) - currently around 10G.

My initial thought is to split the database drives up in the following way:

• Hardware Raid-5 (3 discs) for Data
• Hardware Raid-5 (3 discs) for Logs
• Single disc for Tempdb
• Single disc for on-server backups

Essentially, I'm looking for the best performance by reducing disk contention between different writes (TempDB, Logs & Data).

I'd be curious to get any opinions of whether this appears to be the optimal set-up, or if you'd set up the disc layout differently.

We could spend another £5k for an external Raid setup to allow the Tempdb & backups to be RAID'ed as well, but I think it's a bit of overkill.

Any thoughts?