Recently one of our technicians asked about the requirement to shut down a virtual machine running on Hyper-V before expanding it hard disk. Put simply, the answer is if it is a newer virtual machine you can expand the virtual hard disk without shutting down the vm first:

how to expand a hyperv disk without shutting down the vm

Put technically the Virtual Machine has to be shutdown before expanding a disk in HyperV if the disk is attached to a virtual IDE controller. That means it is an old and likely running as a Gen1 VM. If the VM is Gen2, then the boot drive will be attached to a virtual SCSI adapter and it can be expanded while the VM is online.

WARNING: As Microsoft prompts in the disk expansion process in Hyper V, you cannot expand .AVHDX disks better known as checkpoints / snapshots. We also never expand the disk on a virtual machine when it has checkpoints.

After you have confirmed that the virtual machine has SCSI disk with no Checkpoints:

  1. In Hyper V Manager, click EDIT from the Actions Pane on the right
  2. Select EDIT DISK
  3. Locate the disk in question using the BROWSE button
  4. Select EXPAND DISK
  5. Set the amount of space you want to add
  6. Click FINISH
  7. On the virtual machine that just had its disk expanded, right click on the START button and select DISK MANAGEMENT
  8. Right click on the disk you want to expand, and select EXTEND VOLUME
  9. Click NEXT, NEXT, NEXT
  10. Have a nice day


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