Windows 7 virtual desktop on differencing disk grows and grows!

Question

If you create Windows 7 virtual desktops on VHDs with using differencing disks (on Hyper-V), based on a fresh install of Windows 7 and no optimizations then over 24 hours you'll see all differencing disks grow to the size of the used disk space in the parent VHD! The reason is simple - Windows 7 continually runs a background defragmentation task on the disk, and so it rearranges what it thinks is all it's used disk space block-by-block. In the case of a VM using a differencing disk (a child disk linked to a parent) then it sees the combination of parent and child as its entire disk and it will defrag all the used space! There's really no need for defrag with virtual disks, especially for virtual desktops which will be continually refreshed and recreated, so you can disable this task and save yourself a ton of storage space! After all, the point of using differencing disks is to save storage space, right? Here's the magic command line to disable that defrag task. Run this on your master image: schtasks /change /tn 'microsoft\windows\defrag\ScheduledDefrag' /disable That's it!

aaron fox · Accepted Answer

Quite useful for Win 7 users that have SSDs as well. Thanks for sharing.

psnovar1 · Answer

This information was very usefull for me because i have the same issue in my Vdesktop environment with Vmware Linked Clone. We can try do a document with the best pratices to do a Windows 7 VDI.

PatrickRAtDell · Answer

Hi Aaron.  How are things in LA?

DELL-Rob Ma · Answer

There is also the newly released (beta) of Microsoft's VDI Optimizer... You pick the options, it creates a VB Script that you can manually run inside the virtual machine or push out using something like GPO or vWorkspace tasks..

This is in beta and works for Windows 7...

http://blogs.technet.com/b/deploymentguys/archive/2010/08/31/optimising-windows-7-images-for-use-in-vdi.aspx

craditp · Answer

The VDI Optimizer has come in useful for me and is worth trying!

vWorkspace

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