Enable/disable disk performance counters

by Wayne Maples [Published on 20 April 2004 / Last Updated on 20 April 2004]

Windows 2000 Performance Monitor records physical disk performance data by default. The opposite of the default for Windows NT. Logical disk entities such as storage volumes are not enabled by default. To enable the logical entities, at the command prompt, type:

diskperf -y

After rebooting Windows 2000, disk monitoring for physical drives and logical drives will be available. The newsgroups are filled with messages about errors in the Event logs concerning Logical and Physical counters, that is source=PerfDisk. To clear up these errors and gain back some disk performance: diskperf -n

The most useful counters for identifying disk bottlenecks are LogicalDisk\Avg Disk Queue Length and PhysicalDisk\Avg Disk Queue Length. These counters display the average number of all requests (read and write) that are queued and waiting to be services for the selected disk. If the queue lengths are more than 2 over a long period of time, this could indicate a disk bottleneck. Actually it generally does if the queue length is not the side-effect of a RAM starved system.

To see all the parameters for diskperf, issue the command diskperf /help.

Diskperf works remotely if you have administrative access using the \\computername option.

To turn on physical disk counters: diskperf -yd

To turn off physical disk counters: diskperf -nd

To turn on logical disk counters: diskperf -yv

To turn off logical disk counters: diskperf -nv

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