Use sp_sysmon to determine whether data placement across physical devices is causing performance problems. Check the entire sp_sysmon output during tuning to verify how the changes affect all performance categories.
For more information about using sp_sysmon, see Chapter 39, “Monitoring Performance with sp_sysmon.”
Pay special attention to the output associated with the discussions:
I/O device contentions
APL heap tables
Last page locks on heaps
Disk I.O management
Adaptive Server Monitor can also help pinpoint problems.