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I have a vSphere 5.0 VM that was created with entirely thin-provisioned disks (I don't have any other options when creating them). A year later, one of the disks is now no longer thin provisioned but is Thick Provision Eager Zeroed.

I'm not licensed for storage vMotion (I do have normal vMotion), it hasn't ever been migrated between datastores via offline migration and as far as I'm aware nobody has manually inflated VMDKs.

I do know that at one point the filesystem on the disk in question became full; would this have triggered a conversion to thick provisioned?

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up vote 2 down vote accepted

By filling the disk, the VM was fully provisioned, no? You don't get that space back unless you zero the free space and potentially run a VMware-based storage operation...


How to shrink a VMware virtual disk (vmdk)

With ESXi and Windows Server 2008, can the provisioned size for a disk be reduced?

How can the "actual" size of VHD/VMDK files be reduced after deleting unwanted files?

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So the type conversion is automatic, because it became fully provisioned? vSphere won't recognise it as "thin" again without zeroing the free space and running manual conversion? – Andrew Dec 5 '13 at 1:51
It's not thin anymore. You need to take specific actions to zero and reclaim the space. – ewwhite Dec 5 '13 at 2:06

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