Share via

Setting disk size when migrating from unmanaged disk to managed disk.

Kyle James 0 Reputation points
2025-06-02T15:37:42.1533333+00:00

We have a 1023 GiB unmanaged disk attached to a 2012 Windows R2 datacenter VM, and it must be migrated to a managed disk. Since we are only using ~20GB of that disk, is there a way to specify that the new managed disk should be 128GB instead of an entire terabyte?

Azure Disk Storage
Azure Disk Storage
A high-performance, durable block storage designed to be used with Azure Virtual Machines and Azure VMware Solution.

1 answer

Sort by: Most helpful
Most helpful Newest Oldest
  1. Keshavulu Dasari 4,845 Reputation points Microsoft External Staff Moderator
    2025-06-02T16:30:27.96+00:00

    Hi Kyle James

    When migrating from an unmanaged disk to a managed disk in Azure, the managed disk will, by default, be created with the same size as the source unmanaged disk, if you are only using 20 GB of the 1023 GiB disk, and you want to reduce the size of the managed disk to something like 128 GB, you can do this but not directly during the migration.

    For more information:

    https://learn.microsoft.com/en-us/azure/virtual-machines/windows/convert-unmanaged-to-managed-disks

    https://learn.microsoft.com/en-us/azure/virtual-machines/unmanaged-disks-deprecation

    Please let me know if you have any quires or Steps to Reduce Disk Size During Migration, I am glade to assist.

    1 person found this answer helpful.
    0 comments

Your answer

Answers can be marked as Accepted Answers by the question author, which helps users to know the answer solved the author's problem.