Monitoring and Tuning Your Server

Disk I/O

IIS 5.0 writes its logs to disk, so there is almost always some activity, even when clients are hitting the cache 100 percent of the time. Under ordinary circumstances, disk activity, other than that generated by logging, serves as an indicator of issues in other areas. For example, if your server needs more RAM, you’ll see lots of disk activity because there are lots of hard page faults. But there will also be lots of disk activity if your server houses a database or your users request many different pages.

See the following:

Monitor Settings and Relevant Counters