There are lots of strategies that can be used. But I am a fan of RAID10 or Raid 0 + 1 or Raid 1 + 0, basically mirroring and striping, and unless someone can't point out some stats otherwise it is the fastest configuration in most cases..

A Quick look at http://en.wikipedia.org/wiki/RAID

It sounds like you are gonna be sharing these 15 spindles accross 10 servers. In most cases where I have control and available spindles I do RAID 10 for data log and tempdb. I am a little concerned about the number of servers sharing the storage but was thinking 6 drives RAID 10 for data, 4 drives RAID 10 for Logs, and 4 drives RAID 10 for Tempdb with 1 hot spare..

I will say I am by FAR not an expert on these things but I am usually looking for resiliency and performance.

When I got my new cluster I worked over all the drives with SQLIO, one drive at a time, then a couple at the same time, then ALL of them. It helped me understand what I could expect in terms of performance overall.

CEWII