Performance Monitor: Monitor the performance counters SQLServer:Buffer Manager (Page reads/sec) and SQLServer:Buffer Manager (Page writes/sec) to detect poor performance. These counters measure physical IOs and not logical IOs. Heavy activity can indicate lack of database memory, a poor table implementation or can show that applications are not accessing a database correctly. Monitoring these counters will give insight into changes in workload as well. Many times, alot of writes will occur at the same time that poor performance is noticed.
For both Page reads/sec and Page writes/sec performance thresholds are:
> 1000 – Very High Activity
> 500 – High Activity
> 90 – Elevated Activity