Converting VM from Thick to Thin - Shrink Disk First?

[s1xth]

I am not sure how the response is going to be in this forum, or if I should have posted in the VM forum but I will give this a shot :-).

I have been migrating some VM's around my environment and while doing so I have been converting some of them to thin provisioned disks. I have been having some VM's convert fine and some stay thick even after migration occurs. I have found that by using the VMware tools option of "Shrink Disk" prior to migration has eliminated any of these problems. Is this what VMware recommends? Should you perform a shrink on your VM's prior to converting them to thin? Opinions?

Thanks!!

[karavinds1]

Hello,

Found this article. May be this is helpful.

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1013052

Regards,

Aravind K

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[Duncan Epping]

I've never seen a recommendation about this, but it's definitely what I would recommend.

On any filesystem the actual blocks are not wiped when a file is removed it's the pointer which gets removed. Because of this it seems for the outside world (VMkernel) that the blocks are in use and thin provisioning will not make a difference. With the "shrink" option all the deleted data will get zeroed out and the VMkernel will recognize it as "empty" and not do anything with it. This of course leads to a "thinner" disk.

I wrote a short article about it a while ago:

http://www.yellow-bricks.com/2009/07/31/storage-vmotion-and-moving-to-a-thin-provisioned-disk/

Duncan

VMware Communities User Moderator | VCP | VCDX

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[s1xth]

Thanks!! I will continue to do what I have been doing and defragging the disk first, then shrinking it and then migrating it to new storage and change it thin provisioned.

Thanks!!