Why You Don't See Any Disk Data

The disk utilization on Windows NT is measured by measuring each disk transfer with a high-precision timer. This gives very accurate results, but does have some overhead associated with it. In addition to the calls to the timer routines, measurement of disk activity involves adding an extra disk driver to the I/O system. All this spells overhead. On a 20-MHz 386 this was observed to cost up to 1.5% of the disk throughput. On a 33-MHz 486 there is no measurable impact.

We decided not to burden the system with disk performance measurement unless you really want it. Which, believe me, you do. So right away you should activate disk performance measurement on your computer of interest by executing the following command:

diskperf -y

If you need to look at a remote system named, say, \\cerebellum, try

diskperf -y \\cerebellum

Unfortunately, that's not the end of the cure. You must now shut down Windows NT on the system you are measuring. Next time you start it, you will have operational LogicalDisk and PhysicalDisk counters.