Nice question, although RAID5 is a not really a good choice for databases ! (except limited cases with mostly read-only databases).

Better use RAID 01 (i.e. RAID0-aggregate of RAID1-mirrored drives), which...

Ideally everyone would use ideal solutions like PostgreSQL 9, and pay for added-value services.

If we don't agree with microsoft prices, or business-class-products categories.. we just have to set up...