Windows Server 2012 R2 Hyper-V – Online Resizing of VHDX

The most common excuse given for using pass-through disks instead of VHDX files was “I want to be able to change the size of my disks without shutting down my VMs”.  OK, WS2012 R2 Hyper-V fixes that by adding hot-resizing of VHDX files.

Yes, on WS2012 R2 Hyper-V, you can resize a VHDX file that is attached to a VM’s SCSI controller without shutting down the VM.  There’s yet another reason to place data in dedicated VHDX files on the SCSI controller.

You can:

  • Expand a VHDX – you’ll need to expand the partition in Disk Manager (or PoSH) in the VM – maybe there’s an Orchestrator runbook possibility
  • Shrink a VHDX – the VHDX must has un-partitioned space to be shrunk

This resize is a function of the host and has no integration component dependencies.

That’s one more objection to eliminating the use of pass-through disks eliminated.

3 thoughts on “Windows Server 2012 R2 Hyper-V – Online Resizing of VHDX”

  1. I am running a 2012R2 Hyper V cluster utilizing clustered shared volumes. I manage the cluster with SCVMM 2012 R2. I cannot find a way to shrink the VHDX file using SCVMM 2012 R2. Do I follow these instructions from the server that is actually hosting the VMM? If I do this, will it cause any issues with the CSV volume? Once the VHDX is shrunk, is there anything I need to do on the SAN to reclaim the space, or will windows handle that?

    Thank you for your assistance

    1. Do it on the host in question. CSV won’t care – a file is being resized. The storage is reclaimed by the file system. As for the SAN – that’s a question for the vendor/manufacturer.

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