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Azure Premium Disk Storage Limitations RRS feed

  • Question

  • Hi,

    I'm reviewing all my premium storage configurations across our Azure VM's. Most of the VM's run differing versions of SQL Server.

    We use Standard_E8s_V3 servers https://docs.microsoft.com/en-us/azure/virtual-machines/windows/sizes-memory.

    These claim to have a limit of 12800 uncached disk IOPS and 192 MBps of disk throughput.

    A P30 disk has 200MBps of disk throughput.

    If i'm reading that right it means that the server in question although it can have up to 16 disks reaches it's throughput with only a single P30.

    So my question is are the VM limits for throughput accurate and does it mean that unless you pay for a machine that significantly larger e.g. Standard_E64s_v3, any additional disks are simply a waste. Obviously having SQL on these means the difference in cost between an E8 and E64 is prohibitive.

    My SQL boxes have very intense IO so the better throughput the better results. I strip 3 P20's on the data disk and have a P20 on the log disk now which in theory could get 450 MBps (on data) but it sounds like these are wasted and are capped at 192MBps.

    Regards.

    Simon.

    Saturday, August 4, 2018 6:21 AM

Answers

  • Hi, 

    Yes, if the VM Level throttling is the problem adding more disks wont help in this case. 

    As you say the post is detailed. But the short answer is that you are correct and have to take VM size in consideration for additional data disk performance aswell. 

    Best regards

    Saturday, August 4, 2018 9:04 AM

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