Are the smaller Azure premium storage disks slower than standard disks of the same size? RRS feed

  • Question

  • I wanted to give a boost to one of my Azure virtual machines that is being used as a build server for processing thousands of small files in bursts. So I decided to add a small 32 GiB premium storage (SSD) disk.

    But while reading  Microsoft documentation for Azure disks, something puzzled me:

    For a 32 GiB standard disk (S4):

    IOPS per disk 500
    Throughput per disk 60 MB/sec

    For a 32 GiB premium disk (P4):

    IOPS per disk 120
    Throughput per disk 25 MB/sec

    Does this mean that for small disks there is no point of upgrading to premium SSD because performance will be actually lower? It does not make logical sense to me. Is it true or I misunderstand something?
    Thursday, March 8, 2018 5:24 PM

All replies

  • Yes, the performance of standard storage is the same per disk across the board, whereas premium storage increases as the disk size increases. This does mean that for smaller premium disks the performance may be low than the same size standard disk.

    The main reason you would use premium disk at this size is for the SLA. To be able to get the 99.9% SLA for single instance VM's then you must use premium disks. Generally premium storage is recommend for production work loads.

    Sam Cogan Microsoft Azure MVP
    Blog | Twitter

    • Proposed as answer by vikranth s Sunday, March 11, 2018 12:27 PM
    Thursday, March 8, 2018 5:39 PM