Common questions

What is a good average disk queue length?

What is a good average disk queue length?

10-20ms is average. Over 50ms is bad. For both Current and Avg. Disk Queue Length, the higher the number the more disk operations are waiting.

What disk queue length is too high?

Disk latency above 25 ms can cause noticeable performance issues. Latency above 50 ms is indicative of extremely underperforming storage. Disk queues should be no greater twice than the number of physical disks serving the drive.

What is current disk queue length?

Overview. “\Local Disk\Current Disk Queue Length” is a direct measurement of the number of requests present at the time that the performance data is collected. It also includes requests in service at the time of the data collection.

What is an acceptable disk latency?

For hard drives, an average latency somewhere between 10 to 20 ms is considered acceptable (20 ms is the upper limit). For solid state drives, depending on the workload it should never reach higher than 1-3 ms. In most cases, workloads will experience less than 1ms latency numbers.

What does a long queue length indicate?

Processor Queue Length is used to show the number of processes waiting for the CPU at any given time. A % Total Processor Time greater than 90 percent or a Processor Queue Length greater than 2 is indicative of a bottleneck at your CPU.

What is normal disk response time?

Disk response time in milliseconds. For this metric, a lower number is definitely better; in general, anything less than 10 ms is considered good performance.

What is average disk latency?

If you’re all-disk, latency measure in milliseconds is generally common. Up to about 20 ms is generally acceptable in a VMware environment. As you move to all-flash, though, 20 ms is a lifetime. A good all flash array may have spikes to 3 or 4 milliseconds, but, in general, you should see less than that.

How do you calculate average wait time?

The average waiting time is ( 3 + 16 + 9 + 0 ) / 4 = 7.0 ms. If we were using the FCFS scheduling, then the average waiting time would be 10.25 ms. SJF is optimal in that it gives the minimum average waiting time for a given set of processes.

Share this post