Can I upgrade my Exchange server to the newest operating system as it will save me time and I don’t need to build a new virtual machine? This is a very interesting topic and one that is asked by many admins. The short answer is “no,” you cannot do this, and the longer answer is “no,” you should not do this. Simply put, an Exchange in-place upgrade is not feasible. Let’s look at the reasons behind this:
- Microsoft doesn’t support it.
- Potential data loss.
- A database availability group (DAG) cannot be upgraded.
- Exchange legacy does not support the newest operating systems.
- Cluster versions are different on each operating system.
- Exchange will most likely not work after you try the upgrade, and even if it did work, you will still be running at a risk.
Let’s take a look at each of the items above in more detail.
Exchange in-place upgrade means lots of errors
The first point is crucial: Microsoft doesn’t support an Exchange in-place upgrade. If you had to log a support call with them and they checked and saw that you did it they would not support you, no matter the issue. I personally have tested this in a lab and Exchange does all sorts of strange things once the operating system has been upgraded. For example, errors in the event logs that you don’t normally see.
Let’s jump to point No. 3. This is a very important step. Let’s say you wanted to take a shortcut and you running a database availability group, you would need to break your DAG to be able to do the upgrade as the cluster versions will be different and the DAG will also stop working and log files will go missing. Don’t do it! This leads to point No. 2. You will end up with data loss.
The last thing you want is to break your database availability group and then upgrade only to find out the exchange .edb file is missing or logs are missing and you don’t have a backup.
It’s going to get broken
The next point about an Exchange in-place upgrade is server support for newer operating systems. Yes, it is nice to have the latest in your environment but it doesn’t mean Exchange supports it. You might decide, “I don’t like Server 2012, I want server 2016” and you try an Exchange in-place upgrade only to find IIS is broken or the server ships with a newer version of .NET Framework that also doesn’t work on legacy versions. Worse, you cannot roll back because everything is broken. You now have to recover. This can be dial tone recovery from backups or going through the painstaking process of exporting mailboxes to PST and then having to re-import them.
The next step we will look at is the cluster versions. We briefly touched on it above but, yes, Exchange installs failover clustering but you don’t manage your DAG from there. When you decide to upgrade because you feel it’s just too much hassle to build new servers, you will find the versions different.
Like anything else that is using clustering, you may find that you are unable to join the servers back into a DAG as the objects exist in failover cluster and so you go and remove the objects in an attempt to fix it and you just do more damage. If there was a way to do an in-place upgrade and tackle all these obstacles, Microsoft would have put something together.
Remember, when you upgrade, you carry the problems and baggage from the existing operating system across and never move forward.
And don’t forget about the licenses
While it might be nice to save time and have all the new features of the newer operating systems, remember, you need to cover the licenses for the newer operating systems and client access licenses (CALs). One day when you leave the company, you leave behind a glorified mess that the next person has to try and fix and will end up having to redo everything you have done. This leads to users fiddling in ADSIEdit to try and clear out the names or servers that were left behind and not properly cleaned up and, in the end, everything breaks.
The last point is that you may think that you succeeded in doing the Exchange in-place upgrade (and you not going to tell anyone) but as mentioned, when you try to bring in a new Exchange server that you will want to migrate to or if you want to migrate to Office 365 or to another platform, you might end up with endless issues that cannot be explained.
Exchange in-place upgrade: Worth the wait
The bottom line is, plan your upgrades to the newer versions of the operating systems and decommission the old ones cleanly. As they say “Rome was not built in a day.” Yes, your legacy Exchange server is a pain and you just want to get rid of it, but keeping it for the extra few days or even months won’t hurt — unlike an Exchange in-place upgrade!
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