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I'm managing a number of Thin-Provisioned VMs in vCenter 5.1.0. Each contains one virtual Harddisk. We run a pretty tight ship in terms of allocating storage, so the difference between 1 or 2 GBs is relevant for us in making storage decisions.

I'm looking for an accurate reading of how much of the harddisk the OS is using, and I'd like to use only vCenter utilities (vSphere, PowerCLI, etc). As an example (below), one VM will display hints at its disk usage in many places, but all with slightly varying figures:

"VM1" has been allocated 75GB Thinly. In the General tab in vCenter, the Provisioned Storage amount is listed as 79.88GB, and Used Storage at 66.40GB. When browsing the Datastore, the .vmdk is 64,514,050KB, and lists a provisioned amount as 78,643,200KB. Finally, in the OS (Windows 7), the size of the disk is 74.8GB, and only 59.7GB used.

I know that the "Provisioned" and "Used" statistics also reflect log files and swap files, etc. But could someone please explain in a bit more detail how these amounts are calculated, and more importantly, where I can reliably get a figure in vCenter for provisioned and used storage as the OS would see it?

Thanks!

bjscollura
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2 Answers2

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Provisioned size = What you set the disk sizes to.

The disk size you see in the OS is what's been allocated so far in the thin-provisioned setup.

The Used Storage is the above plus the amount of virtual RAM allocated to the VM (*because of the Virtual Machine swap file).

ewwhite
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VM Provisioned = Each disk size plus ram size. The most the VM could use.
VM Used = The thin provisioned size. Used by the OS plus ram size.

The OS sees the full configured size of the virtual disk.

New RandomVM

4GB ram 30GB disk 0 with 10gb used. 80gb disk 1 with 30gb used. Provisioned = 114gb Used = 44gb

Caveat- Files deleted in the OS is still used space by the VMDK. The VMDK does not automatically recover empty space. In the above example, if disk 1 got up to 70gb used and then 30gb of files had been deleted the used space would be remain 84gb. Provisioned space would stay the same.

user205788
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