Sunday, December 12, 2010

Why can’t I expand the provisioned size of a hard disk for a virtual machine on ESXi/ESX?

After noticing that I get asked:

Why can’t I expand the provisioned size of a hard disk for a virtual machine on ESXi/ESX?

… by clients on an average of twice a month, I thought perhaps I should write a post about this which includes instructions on how to fix this so I can point people to it in the future.

Problem

You would like to expand a hard disk for a virtual machine so you right-click on the virtual machine and choose edit settings:

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The properties of that virtual machine open, you navigate to the hard disk you would like to expand/increase drive space but notice that all the fields are grayed out:

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Solution

One of the reasons why the options are grayed out is because the virtual machine has snapshots taken of it. To check, right-click on the virtual machine, select snapshot then snapshot manager.

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Once the Snapshot Manager window opens, you’ll be able to see there are snapshots for this virtual machine. In the case of the screenshot below, there’s currently one snapshot named Test created.

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Select the snapshot Test and choose Delete to commit the delta to the virtual machine.

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Once you’ve deleted the snapshot, you will now notice that you can edit the Provisioned Size fields in the virtual machine settings:

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6 comments:

Anonymous said...

I have to comment on this where we've seen another time when a disk cannot be expanded thru virtualcenter. It's when the hard disk is not using a SCSI controller (using IDE in the case of a typical installation for WinXP). The only way to expand it is using vmkfstools. Never noticed this before but seeing it more now because of View.

Anonymous said...

It workes great. Thanks a lot!

Anonymous said...

what version did you write this against? The snapshot in XD5.6 is called "Do Not Delete - Critical For XenDesktop", which is a little terrifying.

Anonymous said...

Thanks a ton! This worked great for me.

Shocking how long it takes to remove a snapshot.

Once it was removed, the rest was a breeze.

digital signature Microsoft said...

Excellent! Thanks for this - I've been looking at this feature for ages. Followed your instructions and it works a treat!

Dan Aquinas said...

What if I do not want to lose my snapshots? Is there an alternative (perhaps creating a new VM even)?