Every Exchange Admin rejoices the day they can remove Exchange 2010 from the environment. If you are running Exchange 2013 or Exchange 2016 coexistence with Exchange 2010, you should know that you cannot introduce Exchange Server 2019 until Exchange 2010 is out the environment completely. If you think you can beat the system, the setup of Exchange Server 2019 will fail and tell you that legacy versions have been detected and need to be removed so to avoid the frustration, we need to cleanly remove all servers in the environment.
Please do not go and shutdown servers and then try remove them from ADSIEDIT as you will run into legacy issues down the line. Rather spend the time and remove each component properly and let Active Directory replicate.
There may be a couple of scenarios in how your environment is setup, they may be as follows:
- Multi-role server
- Individual servers with CAS/HUB and MBX roles split
- Multi-role server with Edge Server
- Individual servers as mentioned with an Edge Transport Server.
- Remove Edge Subscription (if it applies)
- Uninstall Exchange 2010 from Edge Server (if it applies)
- Remove CAS Servers, Uninstall Exchange 2010
- Remove HUB Servers, Uninstall Exchange 2010
- Remove Public folder database (If in the environment and not used, you can remove it, else migrate to a Public Folder Mailbox before removing)
- Remove Offline Address books from Mailbox Server
- Turn off circular logging on your DAG if it is enabled
- Remove Mailbox Database copies
- Remove Mailbox Databases
- Remove DAG members
- Remove DAG’s (from 2010 servers)
- Uninstall Exchange 2010 from all Mailbox servers
The list might seem long but it won’t take you too long to remove everything, unless something is wrong and you need to troubleshoot.
To start with the removal, firstly make sure that your mail is flowing through your Exchange 2013 or Exchange 2016 servers and that the Edge Transport Server is no longer in use. You need to remove the Edge Subscription from the Exchange Management Console (Exchange 2010 – EMC) before you try and remove the Edge Transport Server. Once complete and replication is done, you can then go to Add/Remove programs in the control panel and uninstall Exchange 2010 and once done, reboot and then take the machine off the domain and then shut it down.
The next step in the process is to uninstall Exchange 2010 from all CAS servers. You have most likely moved to a new namespace and the servers are no longer in use. Just remember that if you are using a load balancer which I didn’t mention above, you will need to remove the Exchange 2010 members from there and ensure the 2016 servers are now part of the list. Once you have uninstalled from Add/Remove programs, follow the same process as the Edge Server.
The next step is to remove the Exchange 2010 HUB servers. Before you can do this you need to ensure that all send connectors only has the Exchange 2016 servers in and no Exchange 2010 servers. You can proceed with the removal, you may get a warning about shadow queues and need to wait for that to flush before you uninstall. The rest is the same as the first two steps.
The next steps that involve Public folders, Offline address books, Circular logging, Mailbox database copies, removal of DAG members and removal of DAG objects are straight forward. Just remember, each step you do involves Active Directory replication so if you remove something and the uninstall says it is still present, you need to wait a bit for replication to complete. When you have removed everything, you can the uninstall the Exchange 2010 mailbox servers.
Once all the servers have been taken off the domain cleanly and shutdown, you can remove them from your hyper-visor or if they physical servers you can put them to use elsewhere, perhaps for your Exchange 2019 Servers. The work is not done yet, now go and clean-up Active Directory and remove all the old Exchange Objects including DAG’s and then go to DNS and remove all the entries as well so you do not run into issues (small irritating ones) when you ping a server and an old server name replies. If there are reservations in DHCP, clean that up and ensure the new set of servers are present.
On your Load balancer, if you have one, as mentioned, remove the old Exchange CAS/HUB servers. If you have a public IP NAT to an old Exchange 2010 server where you didn’t use a load balancer, make sure you clean these up and when you have your Exchange 2019 servers in place, you can use them for that.
Clean up the old servers from your Anti-Virus, this is if you have a central console. If you are running System Center Configuration Manager (SCCM) or System Center Operations Manager, remember to clean out the Exchange 2010 servers.
In preparation for moving to Exchange 2019 if you are not moving to the Microsoft 365, first make sure that your current Exchange 2013 or Exchange 2016 servers are up-to-date with the latest Cumulative Updates (CU) and then you can move forward and build Windows 2019 Servers that can be your new domain controllers but only if you running Exchange 2016. Exchange 2013 does not support Windows 2019 domain controllers.