Virtual Machine version 7 back to 4

[jtbbeaumont]

I am interested in VMware's official position on using VMware Converter stand alone to convert VM's from version 7 to 4.  I have done it with success and found this article on the web but working and supported are not the same.  Can someone help me here?

http://blog.vmpros.nl/2010/04/09/vmware-how-to-downgrade-vm-hardware-level-7-to-4/?wpmp_switcher=mob...

Thanks,

Jeff

[RParker]

Just recreate the VM as 4... remove from inventory, create the same name, add the disk, voila 4!

why do you need to go back?

[jtbbeaumont]

Hmm

So in order to revert I would

Remove the VM in question from inventory, create a new VM with the same name, add the disk from the original VM and I am back to version 4.

We have a mixed environment of 4.0 cluster and a 3.5 cluster.  It would be nice to make the VM's on 4.0 version 7 but have the ability to revert if needed.

Thanks

[kermic]

I wouldn't do that!

VM HW v7 differs significantly from v4.

What you are suggesting is equivalent taking out a disk from a brand new IBM server and plugging it in a 3 years old one with different mainboard.

This method is neither supported nor recommended! You are asking for at least surprises if not trouble by doing this.

There are 2 civilized ways of reverting back - go back to snapshot taken when VM was still in v4 or use Converter and set destination to be v4.

WBR

Imants

[kermic]

Do you have any specific reason for v7 or requirement that can not be fulfilled with v4?

If not, the best practice is to leave all VMs on v4 in mixed clusters / environments having 3.x and 4.x hosts.

WBR

Imants

[jtbbeaumont]

Do you have any specific reason for v7 or requirement that can not be fulfilled with v4?

If not, the best practice is to leave all VMs on v4 in mixed clusters / environments having 3.x and 4.x hosts.

WBR

Imants

Yes, our backup method called Avamar, an EMC product allows a setting called Change Block Control that is not available on our version 4 VM's, which makes backing them up quicker.  So back to my original question, it appears that VMConverter will do the job but it is supported via VMware support should something happen.

[kermic · Accepted solution]

...Avamar, an EMC product allows a setting called Change Block Control that is not available on our version 4 VM's.

Allows or Requires?

If requires, then I'd suggest to start considering upgrade of 3.x hosts, otherwise you have to account fot significant addtitional administrative overhead and recovery time for each VM (while converter does it's job), or consider alternate backup methods...

Regarding "supported", most probably your VMware contact / sales person will be able to provide the best "accountable" answer.

If I had to guess right now, I'd say "yes" in case of using Converter Enterprise (Converter Standalone has per-incident support purchased seperately) as long as the potential problem is within VMware products (I consider VM hardware of either version to be "manufactured" by VMware, same applies to Converter).

Another reason - KB (http://kb.vmware.com/kb/1028019) also suggests using converter for version downgrades, I don't think they would suggest something unsupported, otherwise there should be a clause of type "use on your own risk".

Additional thought of "supported" issues - check if all your affected guest OSes are currently supported by Converter Enterprise.

WBR

Imants

[continuum]

using converter to change virtual hardware 7 to 4 is a good idea if you get paid per hour.

otherwise a small edit of the vmx plus referenced vmdks does it

[kermic]

So you're suggesting that downgrade is fairly simple and VMware intentionally did not put this option in vSphere client and documentation, training courses are intentionally built with misleading info that HW upgrade is a one-way-ticket, and this trick is just a "secret" know-how for advanced engineers so they can ask for bigger salaries. Right?

Think of this from guest OS point of view. v7 and v4 have different hardware (that's why they are called "Virtual Machine Hardware Version" after all). Essentially this downgrade is the same as any V2V or P2V migration - guest OS is changing hardware. You can of course just replug the OS disk to different MB and hope that OS will boot up (in most cases with simple / common config it actually will after few reboots and tweaks, hopefully) but there must be a reason why nobody supports this neither in virtual nor physical world.

WBR

Imants

[continuum]

kermic wrote:

So you're suggesting that downgrade is fairly simple and VMware intentionally did not put this option in vSphere client and documentation, training courses are intentionally built with misleading info that HW upgrade is a one-way-ticket, and this trick is just a "secret" know-how for advanced engineers so they can ask for bigger salaries. Right?

Yes - exactly.

by the way - a "change virtualHW 7 to 4" wizard is included in Workstation.
I guess it is missing in Vsphere-client because VMware did not anticipate that users may need or want to do that.

Also theis is not secret at all - read the vmx and vmdk documentation on my site