I hope the book didn't say RAID 0, because that's something you never want to use for a database.
IO throughput is a function of the number of spindles you have in an array, the more spindles, the higher the data transfer rate.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability