SQL Server I/O Basics

 SQL Server I/O Basics Chapter 1
http://www.microsoft.com/technet/prodtechnol/sql/2000/maintain/sqlIObasics.mspx 
SQL Server I/O Basics Chapter 2
http://www.microsoft.com/technet/prodtechnol/sql/2005/iobasics.mspx
Storage Performance for SQL Server
http://sqlblog.com/blogs/joe_chang/archive/2008/03/04/storage-performance-for-sql-server.aspx