At some point in your career as a hard-working IT professional you’re likely to encounter a scenario in which an Exchange 2016 server has completely failed. For example, you might have a physical server with a dead hardware component preventing it from booting, or a virtual machine with a corrupt operating system volume that is preventing it from starting up.
There are many ways out of these types of situations, and I won’t dictate that one particular solution is the best one in all cases. You’ll have a variety of factors to take into account in your particular scenario, for example perhaps the hardware component that failed can be quickly replaced and the server brought online, negating the need for any other software-driven recovery process to take place.
But let’s assume for the sake of this article that your situation involves a failed server that will not boot, and you either have replacement server hardware that you can use or are planning to spin up another virtual machine to run Exchange 2016.
In either case a recovery installation of Exchange Server 2016 may be the appropriate course of action for you to take. At a high level the process goes like this:
- You install a new Windows Server instance with the same characteristics as the failed server (the same server name, Windows Server version, drive letters, and performance/capacity)
- You perform a recovery install of Exchange 2016 by running setup with the /mode:recoverserver switch
- You re-apply any custom configurations that were not automatically re-applied by the recovery install
- You restore the Exchange databases if those volumes were also lost in the server failure.
Let’s take a look at an example of a recovery installation for a standalone Exchange Server 2016 Mailbox server. If your server is a DAG member, refer to my article on how to recover a failed database availability group member instead.
Preparing the Server for Exchange Server 2016 Recovery
To begin you’ll need to prepare the server that you’ll be recovering Exchange Server 2016 on. Whether that is the same server or a different server depends on your specific circumstances, but either way you’ll need to:
- Install the same Windows Server operating system and service pack level on the server
- Configure your storage volumes to use the same drive letters as the previous server
- Join the server to the domain (note that you will first need to reset the computer account that already exists in Active Directory)
- Install the Exchange Server 2016 pre-requisites
Performing a Recovery Install of Exchange Server 2016
On the server that you’ve prepared copy the Exchange Server 2016 setup files to a location where they’ll be accessible on the server. You should use the same setup files for the Exchange Server 2016 cumulative update that was previously installed on the server, do not try to use this recovery process to upgrade or downgrade the server.
Open an elevated command prompt and change to the folder containing the Exchange 2016 setup files. Run the following command.
C:\> setup /mode:recoverserver /IAcceptExchangeServerLicenseTerms
Restoring Custom Exchange Server 2016 Configurations
There is often confusion around what counts as a “custom configuration” in this scenario. Exchange Server 2016 stores most of its configuration in Active Directory, such as virtual directory URL settings, transport settings, the names and locations of databases, and so on.
However anything that is machine-specific or stored locally on the server such as IIS settings, SSL certificates, modified config files, or registry keys, will not be restored by the recovery install. You should always document and automate the post-install configuration of your Exchange servers so that any such customizations can be reapplied in this type of scenario.
On the most basic of Exchange 2016 deployments you’re likely to have to at least reinstall the SSL certificate for the server. If you have multiple Exchange 2016 or 2013 servers that have the same SSL certificate installed then you can simply export the certificate from one of those servers, and then import it to the recovered server. Note that the steps for this are the same for Exchange 2016 as they are for Exchange 2013. After reinstalling the SSL certificate you can then also enable it for Exchange services.
Restoring Exchange Server 2016 Mailbox Databases
If the volumes that contain your mailbox databases and transaction logs were not lost in the server failure, and are configured with the same drive letters or mount points as before, then you will likely find that the databases are able to successfully mount and continue operation without data loss.
If the databases and log files are available, but will not mount, you may need to perform a soft recovery of the database first using ESEUtil.
If the databases and log files were lost in the server failure, then you will need to restore them from your last backup.
In this article I’ve provided an overview of performing a recovery installation of a failed Exchange Server 2016 server. As you can see the process requires some knowledge of the server you’re recovering, such as drive letters and any custom configurations, that should always be captured in documentation or scripts in readiness for this type of disaster recovery scenario. When all of the required information and data is available a recovery of the failed Exchange 2016 server is achievable.