Conversion to thin from full Windows 2012 r2 HyperV and VHDX

[Adam Garsha]

(1) I understand how to convert a full VV to thin on the 3par side of the fence. I am wondering for existing full/live VV's if I need to do anything on the windows OS side to notify the hyper-V hosts that the volumes have been converted to thin? Namely, if I do an online conversion to thin for my VHDX volumes, do I then need to reboot all the hosts in the hyper-v cluster in order for them to recognize that the storage has become thin? or just rescan? or... and...

(2) Does one need to run 'optimize volumes' after the conversion? From just one cluster host? or???? Also, does that cause performance problems for the guest VM's to use the 'optimize volumes' feature from within Windows? and...

(3) Should guest windows 2012 instances within the hyper-v cluster also be running 'optimize volumes'?

Basically, I am interested in the host-side steps surrounding _CONVERSION_ of VV's from thick to thin. I scoured documents and can't find a good 3par cookbook for what needs to be done when you are starting out with thick/full VV's. Just little chunks of information, ha!

A

[Adam Garsha]

Another question related to above. We've got a Windows2008r2 guest VM that lives on a vhdx in our Windows2012r2 hyper-v cluster. I converted the large disk to thin and then I used what I was told from class would re-claim thin space on the filesystem, namely I tried:

fsutil file createnew zerotemp.txt 1200000000000
fsutil file setvaliddata zerotemp.txt 1200000000000
fsutil file setzerodata offset=0 length=104857600 zerotemp.txt
del zerotemp.txt

The filesystem filled just up to the point I had intended. I expected to find that on the 3par array side that I would get back that space (kind of like I am used to seeing with rhel in our vmware environment when I create a big file full of zeros with dd), but the space was not reclaimed. Nuts... why didn't all the zero'ing buy space back. 3par thinks the VV is 93% full whereas it is about 80% utilized.

How do I get that space back and re-thin a windows2008r2 guest that lives on a VHDX in a windows2012r2 environment?

[Dennis Handly]

> I am interested in the host-side steps surrounding _CONVERSION_ of VVs from thick to thin

I've seen docs that mention you should clean up space on the host side before converting.  Remove temp files and other unneeded files.