In Windows NT 4.0, disk counters were off by default, and had to be enabled type typing diskperf -y.

In Windows 2000, physical disk counters are enabled by default, but logical disk objects are disabled, until you type diskperf -yv

The syntax of the diskperf command is:

diskperf \[-Y\[D|V\] | -N\[D|V\]\] \[\\computername\]

Where:                                    -Y  Sets the system to start all disk performance counters.                                    -YD Enables the disk performance counters for physical drives.                                    -YV Enables the disk performance counters for logical drives or storage volumes.                                    -N  Sets the system to disable all disk performance counters.                                    -ND Disables the disk performance counters for physical drives.                                    -NV Disables the disk performance counters for logical drives.                                    \\computername Is the name of a remote computer.
NOTE: All enabling actions require a restart.