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Disk Performance at Azure Premium disks RRS feed

  • Question

  • Hi,

    I am testing performance of premium disks at Azure.


    Info:

    • Region: East US
    • VM: E4sV3 (4 vcpus - 32 GB memory)
    • Tested disks: 1 TB and 2 TB.
    • All of the disks are read/write host caching
    • The arrays was created using File and Storage Services on Server Manager.
    • Tool: Crystal Disk Mark x64

    The performance results are the following:


    The results show that all of the disks and arrays have the same performance.

    The questions are:

    Do the 2 TB premium disk have better performance than 1 TB premium disks?

    Do a simple array of 2 disks of 1TB have better performance than a 1 disk of 1 TB?

    Do a simple array of 2 disks of 2 TB have better performance than a 1 disk of 2 TB?

    Are the above performance results the normal behavior for Azure premium disks?

    Thanks in advance!


    Monday, April 9, 2018 9:06 PM

Answers

  • Hi,

    If you check the documentation on https://docs.microsoft.com/en-us/azure/virtual-machines/windows/premium-storage#scalability-and-performance-targets (scroll a little bit down to "Premium Storage disk limits"), you can see that a 1TB premium disk (P30) has less IOPS and throughput than a 2TB premium disk (P40).

    However, you're using a E4s_V3 VM size, which has a maximum IOPS of 8000. 2x 1TB disks should in theory be able to handle 10.000 IOPS (5.000 per disk), but it will be limited by the VM size. (I actually don't know how to "translate" the Crystal Disk Mark score towards IOPS/throughput)

    To answer your questions:

    Do the 2 TB premium disk have better performance than 1 TB premium disks?

    Yes; 2TB disks should be able to deliver 7500 IOPS/250MBps throughput, while 1TB disks delivery max of 5000 IOPS/200MBps throughput.

    Do a simple array of 2 disks of 1TB have better performance than a 1 disk of 1 TB?

    Yes; an array of 2 disks should deliver 2x the IOPS / throughput of 1 disks. However, this could be limited by the VM size.

    Do a simple array of 2 disks of 2 TB have better performance than a 1 disk of 2 TB?

    Yes (same as above)

    Are the above performance results the normal behavior for Azure premium disks?

    According to the documentation, the answer would be "No". But I've never done any tests on premium disks. (maybe somebody from Microsoft could elaborate)


    Floris van der Ploeg - www.florisvanderploeg.com

    If my post was helpfull, remember to click the "Propose as answer" button.

    • Marked as answer by SCCMadmin09 Tuesday, April 17, 2018 6:59 PM
    Tuesday, April 10, 2018 9:53 AM
  • You already have all the data you need to work that out.

    We have the disk throughput numbers here - https://docs.microsoft.com/en-us/azure/virtual-machines/windows/premium-storage#scalability-and-performance-targets

    We know that striping two disks give twice the performance number and so on.

    And we can see the <g class="gr_ gr_213 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del" data-gr-id="213" id="213">through put</g> limitations of VMs here - https://docs.microsoft.com/en-us/azure/virtual-machines/windows/sizes-general

    So using all that information you can see that if you want to achieve 800 MB/s throughput you need 60 p20 or 4 P30 disks striped and attached to a Standard_D64s_v3 VM (a Standard_D32s_v3 will get you just under at 768 MB/s).


    Sam Cogan Microsoft Azure MVP
    Blog | Twitter

    Tuesday, April 10, 2018 8:07 PM

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