Decreasing Disk Size on Virtual Machines

Decreasing Disk Size on Virtual Machines

After searching for some time trying to figure out the best method for actually shrinking a disk without having to load the VM from scratch, this is how I did it.

I am talking about shrinking the actual drive. For example, I had a Windows Server 2008 R2 Enterprise machine that when it was created, it had one of the drives thick provisioned at 60GB. Of this 60GB only 4GB were being used, thus wasting 56GB of space on my storage.

Remember it is easy to add space to a drive and that is a diffrent subject that I am not going to cover but here is a link that does cover it:

I searched for a couple of hours on trying how to do this without having to load the machine from scratch. There were many posts out there that describe using other tools such as Acronis then create a new machine and mount the old disk to it ect. WOW! That seems like alot to shrink a drive.

Heres my setup:

2 - HP DL380 G7 both running ESXi 4.1

2 - NetApp FAS2020 controllers

We will call the ESXi servers Server1 and Server2 just for simple means. VMware has a great utility out there call VMware vCenter Converter. I chose to use the stand alone version. You can download it at:

You can use this tool to export VM from your VSphere enviroment to VMworstation, VM Workstation to VSphere, and also from VSphere to VSphere. Server1 contained the VM that I wanted to shrink. I do recomend running a defrag and disk cleanup prior to converting. Really we are not going to convert but move the machine from Server1 to Server2. You will also need to make sure that the machine that you want shrink is powered off at the time. Here is the best part, because the source machine was powered down, I did NOT change the name or IP configuration at all of the target system.

Run VMware Converter select your source machine (Server1) and then select your target machine (Server2). When you are prompted to select the drives, uncheck the default option and manually select the drives that you want on the new machine. This let me adjust the actual disk space.

Once the converter is complete, power on the new machine, you will have to activate windows again unless you have enterprise license and re-install vm tools. After that the new machine worked without any issues so then I just deleted the source VM.

Be sure to do a backup of the source just in case somthing goes wrong. I thought that I would share this as I do not think that allot of people realize that this tool can be used for just more than converting hard systems to VM's ect.

For more information on the VMware Converter see:

All comments and further suggestions are welcomed!

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‎10-01-2011 07:56 AM
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