Avg. disk queue length
Measures the pressure on the physical hard disk array.
Equivalent PerfMon counter: Logical Disk: Avg. Disk Queue Length
Explanation: This is the average number of physical read and write requests queued for a physical disk.
Guideline values: Due to changes in technology, such as virtualization, disk and controller technology, SANs and more, this counter is no longer a good indicator of I/O bottlenecks. A better measure of I/O bottlenecks is Avg. disk read time and Avg. disk write time.
Check also: Disk avg. read time and Disk avg. write time .