• 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 - this can often tell you if the bottleneck is occurring within your disk subsystem (of course as Gail has already mentioned, always assume bad indexes/stats).

    I've seen disk queuing become excessive when a query was performing hundreds (sometimes millions) of reads on a table due to an clustered index scan on a table with 30+ million rows. A little magical index tweaking later and the result was a 100% non-clustered index seek, and the reads went down to < 100K, and the disk queuing went significantly down.

    Again, without knowing what your hardware architecture is, it's difficult to really help you out. Our suggestions could be night/day difference on a server with 4 spindles in a RAID 5 versus a server with a SAN containing 64 spindles. Performance in these cases (i.e. like where you should be concentrating your efforts), is relative.

    ______________________________________________________________________________Never argue with an idiot; Theyll drag you down to their level and beat you with experience