Statistics about hard disk drive usage help you balance the workload of network servers. System Monitor provides physical hard disk counters for troubleshooting, capacity planning, and measuring activity on a physical hard disk.
At a minimum you need to monitor the following counters:

• PhysicalDisk\ Disk Reads/sec and Disk Writes/sec
• PhysicalDisk\ Current Disk Queue Length
• PhysicalDisk\ % Disk Time
• LogicalDisk\ % Free Space

When testing hard disk performance, you can log performance data to another hard disk or computer so it does not interfere with the hard disk you are testing.

You might want to observe additional counters, such as:

• PhysicalDisk\ Avg. Disk sec/Transfer
• PhysicalDisk\ Avg. Disk Bytes/Transfer
• PhysicalDisk\ Disk Bytes/sec

You can also check the value of PhysicalDisk\ Avg. Disk Bytes/Transfer. A value greater than 20 KB indicates the hard disk is performing well. Low values result when an application accesses a hard disk inefficiently. Because hard disk counters can cause a modest increase in hard disk access time, Windows 2000 does not automatically activate the counters at system startup.

Performance data about the logical hard disk is not collected by the operating system by default.
To obtain performance data for logical drives or storage volumes, you must type

diskperf -yv