I recently had a customer with two vCenter VMs running on Windows 2008 R2.  They were vCenter servers upgraded from 5.1 to vCenter 6.0 about six months ago.  They’re both using embedded PSCs, and have vSphere Replication and SRM plugged into them.  To simplify administration, they have embarked on a project to get all servers running Windows Server 2012 R2.

After researching, there really isn’t a great, documented way to transplant a vSphere 6 server from one OS instance to another.  Normally, I’m not a big fan of in place upgrading server operating systems, but this was a special case to meet the customer’s objective, and redeploying two vCenters and then likely having to redeploy/reconfigure SRM wasn’t something I’d want to do, plus any pitfalls with vSphere Replication. But the question is – will vCenter 6, especially with an embedded Platform Services Controller and lots of things plugged into it, work after an in place OS upgrade?

I definitely had my doubts.  The answer though in my lab is surprisingly yes!  I tried it both with an embedded PSC, and then tried it again with a once embedded PSC reconfigured to use an external PSC.  I didn’t encounter any problems whatsoever, although I should point out this was a lab environment with a clean fresh setup prior to the OS in place upgrades.

So I went ahead and did it for the customer’s environment (they aren’t  big enough to have a lab environment), and it worked like a champ as well!

Here are some things I would make sure of before proceeding:

• You may want to backup the vCenter database.  Warning: the vPostgress Windows backup script said it ran successful for me but generated an empty 0KB backup file.  (This was one of the reasons I didn’t attempt a transplant of vCenter to a new OS instance!)  Check to ensure this database file is valid before counting it as a backup to fallback to if there’s a problem.  This may be a future blog article once I get some answers for why this happened.
• Verify what version of Windows is running, and ensure you have the required media and license keys.  In particular, if vCenter is running Windows Server 2008 R2 Datacenter, you can’t upgrade to Windows Server 2012 R2 Standard.
• Verify what database vCenter and VUM are using if on the same box.  vPostgress is fine.  But of it’s Microsoft SQL running on the vCenter server itself, make sure SQL is running something that is supported on Windows Server 2012 R2.  Of specific note on some of these older vCenter VMs, SQL 2008 R2 needs to be SP2 or later.
• I would recommend stopping all vCenter related services, VUM related services (if on the same OS instance), the database service (if it’s on the same OS instance),  and AV active protection prior to OS upgrade.
• Make sure the C drive has at least about 15GBs of free space.
• Reboot the OS prior to starting the upgrade to clear out any cobwebs.
• Take a snapshot and/or backup vCenter before proceeding.  (Kinda duh…)  What isn’t so duh is before you take the last snapshot, launch the upgrade prior to doing this and verify you don’t need to do anything prior to installing the upgrade.  This is usually stuff like it may require you to reboot the OS prior to the upgrade  If all you see is the warning to check to ensure your applications are compatible, cancel the upgrade, take your snapshot, and start the other precautionary steps below. If there are other things it asks you to do, do those first, THEN snapshot your VM.
• Don’t forget to kill your snapshot once everything is done, and you’ve confirmed everything is working.

It worked flawlessly using these precautions for both production vCenter servers!