Formula to calculate your IOPS

To calculate the maximum IOPS you can achieve with your current virtual environment (SAN and ESX host), here is a formula:

queue depth*(1/storage latency in ms)

Let say your queue depth is 64, your storage latency is 7ms, theoretically the maximum IOPS you can get is 64*(1/.007)=9142 IOPS

Not bad at all for a single VM, but if you have a big consolidation ratio, something like 15:1, this comes down to 609 IOPS per VM in a scenario where all 15 VMs use a constant load on the storage.

And 609 IOPS per VM can quickly become an issue for high IOPS demanding applications such SQL.

Thus upfront of any VMware implementation, carefully design your storage and use this formula to have a good idea of  the IOPS you can expect.


About PiroNet

Didier Pironet is an independent blogger and freelancer with +15 years of IT industry experience. Didier is also a former VMware inc. employee where he specialised in Datacenter and Cloud Infrastructure products as well as Infrastructure, Operations and IT Business Management products. Didier is passionate about technologies and he is found to be a creative and a visionary thinker, expressing with passion and excitement, hopefully inspiring and enrolling people to innovation and change.
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6 Responses to Formula to calculate your IOPS

  1. Pingback: Understanding disk IOPS « DeinosCloud

  2. Fred says:

    Thank you for this article !
    What are the average metrics for a SQL server VM ? For an application server VM ? A web server VM ?
    I think it woul’d be a good idea if we coul’d have theses metrics (just for example) !
    Thks !!!

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  5. Ashok Raj says:

    Thanks for the formula. But how can I know the Queue depth and Latency of a drive ? I have a requirement to find the IOPS of a single SAS 300 GB driver, 15K speed.


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