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.

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

  1. Thank you for this post, I was needing a clear YES to online resizing in 2012

  2. 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

    • 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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