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HOW TO: Shrink or Reduce a VMware Virtual Machine Disk (VMDK) using VMware vCenter Converter Standalone v5.5.2

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Andrew Hancock (VMware vExpert / EE MVE^2)
MVE^2, Expert of the Year 2017-2011, Scribe 2016-2012, Author of the Year 2017-6,2013-2012 VMware vExpert 2018-2011 27 years of experience.
HOW TO: Shrink a VMware Virtual Machine Disk (VMDK) using VMware vCenter Converter Standalone v5.5.2

In my previous VMware Experts Exchange Articles, most featured Intermediate VMware Topics. My next series of articles will concentrate on topics for the VMware Novice; this is the thirteenth article in this series.

If you would like to read the other articles in this series, they are listed here for your convenience.  

During this series of articles VMware released VMware vSphere 5.5 and VMware vSphere Hypervisor ESXi 5.5. These articles are also applicable to VMware vSphere Hypervisor ESXi 5.x and 5.5. For consistency, I have used VMware vSphere Hypervisor ESXi 5.1 throughout this series.
Increasing the size of a VMware Virtual Machine Disk (VMDK) is straightforward, and is supported in the vSphere Client, by selecting the virtual hard disk, and increasing the size using the up arrow icon or typing in a new value. Please see my previous Experts Exchange article and screenshot below:
However, although there is a down arrow present, you cannot shrink the disk in this way, it's not supported. The only supported method of shrinking a VMware virtual machine disk (VMDK) is to use VMware vCenter Converter Standalone and create a virtual to virtual (V2V) conversion, a similar process to a Physical to Virtual (P2V) conversion.
I have decided to write this Experts Exchange Article, due to the many Expert Exchange questions which are asked on this subject, of “how do I reduce the size of my virtual machine?”

Please see my previous Experts Exchange articles

In this article we will show you HOW TO: Shrink a VMware Virtual Machine Disk (VMDK) using VMware vCenter Converter Standalone

Before your start the following procedure, please ensure you have a valid and tested Full Backup of your virtual machine. This does not mean a VMware Snapshot.

Also check to see the virtual machine is NOT running on a Snapshot disk, If unsure please refer to my Experts Exchange Article

1. Download and Install VMware vCenter Converter Standalone


See my Experts Exchange article below for download links for VMware vCenter Converter Standalone v5.5.2

Download and install VMware vCenter Converter Standalone on the virtual machine, which is attached to the virtual machine disk (VMDK), that you need to re-size or shrink. It is recommended and best practice, to install VMware vCenter Converter Standalone on the virtual machine to be converted; this overcomes network, communication, firewall and permissions issues.
Click the VMware vCenter Converter Standalone icon
VMware vCenter Converter Standalone will start. Click the Convert machine button, in the top left.

2. Specify Source System


At the Source System dialogue, Select the source system you want to "convert" (re-size virtual disk).

Select source type: Powered-on machine

Specify the powered-on machine type

If you have installed VMware vCenter Converter Standalone on the virtual machine to be "converted"  (re-sized) – Andy’s - Best Practice and Recommended!

Select – This Local Machine


In this tutorial I’m going to perform a remote or network conversion, to perform a remote or network conversion across the network

Select source type: Powered-on machine

Specify the powered-on machine type

Select – A remote machine

Enter the IP Address or hostname of the machine to be converted, ensure this machine is reachable from the conversion machine across your network. i.e. VMware vCenter Converter Standalone must be able to communicate with the machine to be converted.

Enter the user name and password of a user account which has Local Administrator permissions for the remote machine.

Specify the OS Family. Windows

We are converting a Windows OS, which has a virtual machine disk size of 127GB, the details are shown of this virtual machine in the first screenshot in this tutorial. This was created by an over-zealous VMware Administrator, which was too large for a Windows 2012 R2 Server OS, system disk!

Click Next to continue with the conversion

If performing a remote conversion across a network, VMware vCenter Converter Standalone will need to deploy an Agent to the remote machine, and will display the following diaglogue

Leave the defaults, and the VMware vCenter Converter Standalone Agent, will be automatically uninstalled when the conversion completes.

Select Yes to continue.

If the user name and password, network, communications, and permissions are correct, the agent will be deployed as follow, if an error is displayed at this stage, check username, password, network, firewalls and permissions.

3. Specify Destination System.


Select the Destination System: Select VMware Infrastructure virtual machine

VMware Infrastructure virtual machine is either a VMware vSphere vCenter Server, or VMware vSphere Hypervisor (ESXi).

The other option – VMware Workstation of other virtual machine, allows you to “export” the virtual machine to a file share for use with VMware Workstation, VMware Player, VMware Fusion or other VMware or virtualisation product.

In this tutorial, we want to re-size the virtual machine disk, on the existing VMware vSphere Hypervisor (ESXi) server.

Specify the VMware Infrastructure server details

Specify the IP Address or Hostname of the server, and a valid user name and password.

if your VMware vSphere Hypervisor (ESXi) host servers are managed by a VMware vSphere vCenter Server, you will need to specify the hostname or IP Address of the VMware vSphere vCenter Server

Click Next to Continue

Specify the Destination Virtual Machine name, for the inventory and Click Next to Continue

Select the Destination Location for the virtual machine, select a valid datastore with enough storage space,

destination-system3.pngand select a Virtual machine version (Beware version 10 and later can ONLY be managed using the vSphere Web Client available with vCenter Server).

VMware products and their virtual hardware version:
For further details see here VMware KB: Virtual machine hardware versions  

We often select Virtual machine version 8 for ESXi 5.x, and I would recommend this virtual machine version unless you have a specific requirement for 9 or 10.

Click Next to Continue

4. Options (change virtual disk size!)

This is where the "magic happens", where we can change the size of the virtual disk (VMDK) and OS Partition.

Select Edit right of Data to copy


This will display the Data to copy page, where changes can be made to re-size the virtual machine disk (VMDK).


Select the drop down box, next to the C:.


You can select Maintain Size, Minimum Size, or Specify a size in GB or MB.

So type in the size of the virtual disk you require.

We are going to reduce the virtual disk (VMDK) to 30GB.


Select Next to Continue

Review the Summary, and Click Finish.


The job will be submitted and the conversion will be started….

5. Job Progress

A common question asked on Experts Exchange is "How long will it take to convert a virtual machine of xGB?"  There is no standard answer, there are so many different variables which affect a conversion speed.

  • size of virtual machine disks
  • speed of source datastore where the virtual machine disks are stored
  • speed of destination datastore where the virtual machine disks are stored
  • network speed

You can improve transfer rates by disabling SSL, see my Experts Exchange article

You can also use "Sync" mode

After a few minutes, a more accurate figure is displayed, when the conversion will be completed.

The first Windows OS partition has been converted.

Conversion almost complete. see log highlights on the lower right panel
Conversion complete.

6. Checking Converted Machine



Checking the converted machine, the virtual disk is now 30GB!



Powering-ON the the converted machine, confirms correct BOOT-up sequence (no BSOD!)

Powering-ON the the converted machine, confirms correct BOOT-up sequence (no BSOD!)


Powering-ON the the converted machine, confirms correct BOOT-up sequence (no BSOD!), Windows Server 2012 R2 started.

Confirmation using DIsk Manager the Windows Server 2012 R2 OS partition has also been changed to 30GB.

Congratulations, you have successfully Shrunk a VMware Virtual Machine Disk (VMDK) using VMware vCenter Converter Standalone

Thank you for reading my article, please leave valuable feedback. If you liked my VMware article and would like to see more Articles from me, please click the Yes button near the: Was this article helpful? at the bottom of this article just below and to the right of this information. Thank You. Do not forget if you have a question about this article or another VMware, Virtualisation, Windows Server 2012 question, why not post a Question for me and the other Experts Exchange Experts in the VMware, Virtualisation, Windows 2008, Windows 2012 Zones. I look forward to hearing from you. - Andy :- twitter @einsteinagogo


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Expert Comment

by:Federico Durante
I have tested this procedure with the v.6.0.0 build version 3018524 VMware vCenter Server and vSphere Client, and VM v.11, and it all works. Thanks

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