The Microsoft Windows disk monitoring command enables and disables data collection for logical and physical disk performance. This command is available in Windows 2000 or higher within a Command Prompt session. In Windows 2000 or higher environments, disk monitoring is disabled by default. In order to collect logical and physical disk performance data in Windows 2000 systems, you must run the disk monitoring command.
A physical hard disk can be partitioned in to one or more logical drives. Some processes write information to the hard disk. If no more space is available because the disk is full, then some process that is running might abort and cause problems with the system.
The two major factors affecting performance in a system are available memory and efficient transfer of data to and from the disk. In database and file systems that do a lot of input and output to disk, it is even more important to measure the rate of disk transfers and to optimize this element of the system.
If the percentage of time a disk drive is busy servicing read or write requests is more than sixty-five percent, make adjustments to the system. If the sustained queue length is greater than two over the current I/O process, you have a bottleneck in the system and need to make changes.
You can use the Disk Reads/Sec and the Disk Writes/Sec attributes in situations to monitor the performance of the physical disk.