Introduction:
There can be several reasons for migrating an existing Exchange server to a new server machine. The existing server machine could be at the end of its warranty period or would need to be decommissioned for many other reasons. Migrating an Exchange server to a new server can sometimes be a strenuous task. So, in this article, we will take a look at a checklist of things you should have done, and the process of moving an existing Exchange server to a new server without hiccups.
Pre-migration checklist:
Before beginning the migration process, here are some things that you will need to take care of:
Ensure that Microsoft Outlook and Office are upgraded to the most recent cumulative updates and patches.
If you need any new certificates or licenses, plan accordingly.
Ensure that all the third-party apps and VoIP platforms are compatible with Exchange Online and Microsoft 365.
Migration process:
The process of migrating an Exchange server to a new server consists of the following steps:
- Installing and configuring the new Exchange server
- Configuring the new Exchange server
- Migrating all data to the new Exchange server
- Decommissioning the old Exchange server
Note: No two Exchange servers can exist with the same name or IP address simultaneously. Also, Exchange server names cannot be modified. So, the new server should have a different name from the old server.
Installing and configuring the new Exchange server
The first step is installing and configuring the new Exchange server. If you are migrating between the same version of Exchange server, there should be no additional hardware or other requirements. Once you have acquired the hardware for the server or provisioned the resources in case of a virtual server according to the planned and designed specifications, you can install the Exchange server and start configuration. When you install a new Exchange server into an Active Directory environment, the new server will automatically register in the Autodiscover SCP. You will have to change the Autodiscover url immediately, and match it with the url of the existing server.
Configuring the new Exchange server
After installing the new Exchange server, there are three aspects you will need to configure, which are the client access, the transport services, and the mailbox services. Here's how you can configure the new Exchange server:
- Configure the client access namespace of the new server with the same name as the current Exchange server.
- Then, you will need to have an SSL certificate for the new server, If the certificate of the old one is still valid, you can reuse them by importing from the old server.
- For configuring the transport system, firstly, configure the transport size limits with values matching the existing server
- If you have an SMTP relay connector on the old server, configure a relay connector to the new Exchange server that matches the old Exchange server.
- Test the transport mail flow to ensure everything is in order.
- Coming to the mailbox services, create and configure mailbox databases ensuring database and log files are located in the volumes as designed.
- Ensure to match the mailbox quota settings with the existing Exchange server's settings.
- Ensure that the backup process is running for the new databases.
Migrating all data to the new Exchange server
Similar to the configuration state, the migration stage also consists of three aspects of client access, the transport system, and mailbox services. Here's how you can migrate all date to the new Exchange server:
- Update the client access namespace in DNS to direct to the new Exchange server instead of the old server. This client access cut over step is a crucial step, so proceed with caution. To ensure minimal risk, configure a low TTL value, say, 1 minute for the cut-over period so that you can roll back the change easily if necessary.
- Ensure that external client connectivity is also cut over.
- Coming to the transport system. For internal services, update the DNS alias that is used to direct the services to the address of the new Exchange server. This will take care of the transport cut-over for the internal services. If the internal services were directed to the previous server using the server's IP address or real name, update the information to reflect the IP address or name of the new server.
For external services, there are two parts:
Inbound email: The cut-over for the inbound email should be performed in the firewall, or on the routing host that routes incoming mail to the Exchange server. This process is if your server's public IP address that the MX records will resolve does not change.
Outbound email: The cut-over for outbound email is done by updating the source transport server. In your send connector, update the source transport server to reflect the new server Exchange server.
Finally, we come to the mailbox data that needs to be migrated. Open the Exchange Admin Center, navigate to Recipient -> Mailboxes, and choose the mailboxes you want to move after selecting the target destination. It is advised to test the mailbox data migration process with a limited number of emails to see if nothing goes wrong, and then move the data in larger batches.
Decommissioning the old Exchange server
Once the migration is complete, the old Exchange server will be ready to be decommissioned. Before decommissioning, check for the following:
- All clients and transport services are directed to the new Exchange server.
- The old Exchange server has been removed from all send connectors.
- Check IIS and SMTP protocol logs to see if the old server is still receiving any traffic, and resolve if so.
- The mailbox databases in the old server do not contain any mailboxes.
- All public folders have been migrated in the case of Exchange Server 2010.
Once the above-mentioned points have been checked, you can proceed to decommission the old Exchange server. You will not have to worry about skipping or having missed any critical process, because if that is the case, you will not be able to decommission the server by uninstalling the application.