Downgrading a VM’s ‘VM Version’ or as it is commonly called by many it’s ‘hardware (HW) level’ is probably not a task that you’ll find yourself performing that often though it is useful to know how to should the requirement ever arise.  The most obvious reason for downgrading a VM’s ‘VM Version’ is when moving a VM from a vSphere (ESX(i) 4.0) environment to an older VI3 (eg: ESX(i) 3.5) installation.

A VM running on a VMware VI3 environment is at VM Level 4 and once upgraded in a vSphere environment it is at VM Level 7.  So why the jump from Level 4 to Level 7?  With the help of Joep Piscaer (Twitter: jpiscaer) we seem to think it’s because Levels 5 and 6 are used for VMware Workstation.  If anyone knows anything more or can confirm this then please let me know.

The following is a step-by-step guide on how to perform this downgrade – as you’ll see it’s quite straight forward which is always good news! 

I will be performing this downgrade on a Windows Server 2003 VM called ‘W2K3 Std x32 – Test VM’ which I have been running in one of my VMware vSphere labs.

This VM is currently running at VM Version 7.

What you will need, if you haven’t already downloaded and installed it, is a copy of the VMware vCenter Converter.  You may have used this useful utility before when migrating your physical server infrastructure into your new shiny VMware VI3/vSphere environment.  The converter tool comes in two flavours, standalone and enterprise.  The good news is that a copy of the free downloadable standalone version will suffice in performing the VM Version downgrade which can be downloaded from here.

Once downloaded and installed then run the vCenter Converter.

Click on ‘Convert Machine’

What we are going to be doing is a virtual to virtual (V2V) copy of the source VM whose VM Version we want to downgrade.  This is a little different to the physical to virtual (P2V) that you may have used vCenter Converter for before.

The conversion process is simplified through the use of a wizard which takes you through the required steps.

Step 1 – Specify the Source: As the machine we are wanting to downgrade is, and would always be, a virtual machine select ‘VMware Infrastructure virtual machine’ from the ‘source type’ dropdown list box.  Also enter in the name/IP of the ESX(i) host or the managing vCenter Server instance along with logon credentials.

Select the VM whose VM Level you want to downgrade.

Step 2 – Specify the Destination: Next we want to select where this source VM is to be copied to.  Since we want to maintain it as VM because we are downgrading the VM Level, select ‘VMware Infrastructure virtual machine’ from the destination type dropdown list box.  Once again enter the details (name and logon credentials) of the destination ESX(i) host or vCenter Server instance.

At this next stage you have the chance to assign a new name to the virtual machine.  For this article I am going to amend ‘HW Lvl 4’ to the end of the VM’s name. You can also select the target datastore along with, most importantly, the opportunity to select the VMs  VM Level – where we select ‘Version 4’.

Step 3 – View/Edit Options:  This step is actually the most interesting as from here you can change a wide array of the VM’s settings.  I recommend spending the time to take a look around to see what can be ‘tweaked’ or changed.

A useful option is the ability to convert the VMs disk(s) to and from flat to thin during the V2V process.

Another rather good option in my opinion is being able to modify individual service settings on the VMs OS (in this case Windows Server 2003).

Step 4 – Thunderbirds are GO!  This next step presents you with a summary of the configuration settings which will be used for the V2V process. At this stage you still have the ability to go back and make any necessary modifications to these configuration settings.  To proceed press the ‘Finish’ button and go and make a cup of tea/coffee/water (delete where applicable).

The vCenter Converter now validates the configuration and then proceeds to create a clone (at HW Lvl 4) of your selected VM to the target storage device.  I find that the estimated time remaining does fluctuate a lot and tends to take less time than originally specified – as is the case with most software packages offering estimated time.

Once the V2V process is complete you will see the ‘Completed’ status in the vCenter Converters status field.

How here comes the test!  When I start up the newly created instance of the VM on my ESX(i) 4.0 host we can see that it is now successfully running at VM Version 4 and not the original (ESX(i) 4.0) level 7.

The real test is running the same VM on an ESX(i) 3.5 host which wouldn’t normally be able to run a VM Level 7….. As you can see (below) it runs with no problems at all.

Hope you found this step by step guide useful. 

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