topic Re: Reclamation within NTFS filesystem of Hyper-V guest in Microsoft Virtualization Discussions

Reclamation within NTFS filesystem of Hyper-V guest

madden — Thu, 05 Jun 2025 06:16:44 GMT

Hi,

Are there any plans to introduce a cmdlet that can reclaim space within a Hyper-V guest NTFS filesystem?

Also, I read that Windows 2012 offers UNMAP support at the guest and the parent, but I also heard the performance of the parent UNMAP against the storage array can be overwhelming. So any idea if you could have UNMAP enabled at the guest and disabled at the parent, and then use Invoke-NaHostVolumeSpaceReclaim on the parent LUN to reclaim space freed by the guest?

Thanks,

Chris

Re: Reclamation within NTFS filesystem of Hyper-V guest

ChanceBingen — Thu, 29 Nov 2012 18:59:48 GMT

Hi, Madden!

You may want to take a look at the TechEd presentation on Hyper-V storage. With Windows 2012, you can hole punch from the guest through the VHDX. They show a demonstration of it in this video.

http://channel9.msdn.com/Events/TechEd/NewZealand/TechEd-New-Zealand-2012/VIR302

The NetApp Windows Host Utilities 6.0.1 will disable automatic unmap in the parent, but you can schedule run the Invoke-NaHostVolumeSpaceReclaim in the parent to run off-peak hours and/or throttle the unmap work with the -UnmapSize variable in the latest version of the Cmdlet.