Confused over Azure OS Disk Pricing.


  • I'm having trouble trying to work out how Azure offers its disk options. 

    I understand the difference between an OS disk and a Premium SSD Managed (Data) Disk - I have a P4 32 GiB Premium SSD Managed Data Disk with a B1MS Windows 2012 R2 Server Virtual Machine - which I have no issues with.

    However, on their calculator they state that you can have a P4 OSDisk 32GiB which costs £4.76/month with my B1MS Virtual Machine - however when I came to creating my VM, Azure decided to charge me for the P10 Premium SSD 127GiB OSDisk without giving me the option to change this prior to going live.

    I don't see why they don't give you the option to choose your OS disk size when you come to creating your VM but on their cost estimator it's implied that the OS Disk size (and therefore cost) can be adjusted?


    • Edited by Todd Gilbey Friday, January 11, 2019 9:04 AM Included OS
    Friday, January 11, 2019 8:58 AM

All replies

  • Hello Todd,

    There are some pre-configured sizes for the Disks in Azure, eg OS disk = 128GB, Data disk = 1024GB.

    If you want to use your P4, you should select a smalldisk image from the portal.


    Otherwise, there are ways to resize a Disk. You can check links here and here.

    Friday, January 11, 2019 2:28 PM
  • They scale up the OS disk size as you move up VM sizes, you can specify it yourself if you use Powershell or CLI or Templates, but the Portal is kept as formulaic as possible.


    Friday, January 11, 2019 3:19 PM
  • Thats great, could you point me in the right direction to the documentation on how this is done please?



    Saturday, January 12, 2019 6:04 AM
  • Perfect, thanks. So would the "Small Disk" options refer to the OS or the Data Disks?



    Saturday, January 12, 2019 6:05 AM
  • smalldisk images refer to the OS disk. If you need to shrink your Data disk, you should do it using the above-mentioned links.
    Monday, January 14, 2019 7:07 AM
  • Thats great, and just to confirm, the cost of the smalldisk image (i.e. 32gb) will be reflected as per the pricing in Azure Managed Disk price page below? I.e - a smalldisk image of 32GB P4 SSD will be £4.77 per month?

    Thanks for your help.

    Monday, January 14, 2019 7:51 AM
  • Yes, you will be charged for the base cost as shown in the azure pricing link for the P4 disk. Of course additional charges apply for the Windows Server license.

    When you reach the last stage of provisioning your VM, you will get an estimation for the total charge per hour. You can use this estimation to determine wether you are getting any charges that you didnt account for.

    Monday, January 14, 2019 9:49 AM
  • Not sure if this is what you are looking for

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    Tuesday, January 15, 2019 5:05 AM