MyDoggieJessie (12/21/2012)
Taking this with a grain of salt and the "it depends" answer, another way to see if you have disk contention is to track the average disk queue length for the disks
Sorry to pick on you today, but disk queue length is a near-meaningless counter these days. There's too much between the server and the disks to get a sensible interpretation of that counter (unless you're dealing with direct attached drives), plus SQL is designed to intentionally queue up multiple IOs, thus sending the queue length very high (read ahead reads).
The avg sec/read and avg sec/write are a lot easier to interpret and track
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