Windows 2000 Performance Guide

System Monitor Counters

A number of objects provide performance metrics that are relevant for evaluating the performance of the logical disk subsystem. The Logical Disk object provides information about each partition. When a physical disk has been partitioned into multiple logical disks (partitions or volumes), the metrics provided by the Physical Disk object are aggregates of the load imposed on all the partitions. The System object provides a few additional counters related to disk subsystem performance. Finally, the Cache and Memory objects provide counters that are useful in determining whether the cause of a disk bottleneck is filesystem access or a shortage of memory. Some of these counters have been covered in their respective chapters in detail, but we include them here to remind you that they can help to resolve a performance problem with the disk subsystem.

By default, Windows 2000 collects performance counters only for the Physical Disk object. To enable collection of counters at the Logical Disk object you must use the diskperf command with either the -y or -yv flag. (We described the usage of the diskperf command in Chapter 8.)

The following counters are available under the Logical Disk object in the Performance Monitor:

% Disk Time, % Disk Read Time, % Disk Write Time

These are utilization measures for the disk time, and indicate the percentage of elapsed time that the instance is busy servicing requests in general, read requests, and write requests. ...