How to Recover Exchange Server After Total Failure

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Disasters may strike at any moment. Exchange Server failure is one such disaster that can lead to downtime or temporary shutdown of daily activities, severely impacting your business and organization. Such situations are direr when the organization runs on a standalone Exchange Server without additional protection, such as DAG or automated regular backups.

However, a proactive approach can help you overcome such disasters and restore your Exchange infrastructure after failure, when the server does not boot or is totally lost.

In this article, we share the steps you can follow when your only Exchange Server is lost and to restore the server as quickly as possible to resume the email flow and regular business activities.

Steps to Recover Exchange Server after Total Loss

Follow these steps to gather the required information to rebuild and restore the Exchange Server via recovery installation.

Gather the Required Information for Exchange Server Recovery

To perform Exchange Server recovery installation and restore the server, you must gather the following information:

  • Operating system version: You can use the Active Directory Users and Computers to find the Operating System installed on the lost Exchange Server.
  • The installation directory path where Exchange was installed: You must know the installation directory path to ensure a successful restore. Otherwise, the recovery process will fail. To find it, open the ADSI Edit, right-click on ADSI Edit node, and select Connect To.
  • Cumulative Update (CU): Check the serialNumber to find the Cumulative Update that was running on the failed server.
  • SSL Certificate: Once the installation is complete, you must re-import the SSL/TLS certificate to the server. Otherwise, users on Outlook will see a certificate warning or prompt.

Note: If the Cumulative Update information is not available, you can download the latest CU to perform the recovery installation.

Reset the Account

Once you have the required information, reset the Computer account of the lost server in Active Directory (AD).

  • Open Active Directory Users and Computers.
  • Locate the failed or lost Exchange Server name.
  • Right-click on the server and choose Reset Account.
  • Click Yes to confirm.
  • Click OK when the notification appears confirming the account reset.

Prepare the Server for Recovery

Follow these steps to prepare the server for the recovery installation.

  • Set up a new Exchange Server on a VM or physical machine with similar or identical hardware, same name, and operating system.
  • Create drive partitions with the same disk letters as the lost server.
  • Join the new (target) server in the same domain as the lost server.
  • Install the prerequisites and components required by the operating system on the server.

Run the Recovery Installation of the Exchange Server

To run the recovery installation, download the Exchange Server CU ISO, right-click on it, and choose Mount.

Open Command Prompt as administrator and run the Setup /m:RecoverServer command to start the recovery installation.

Setup /m:RecoverServer /IAcceptExchangeServerLicenseTerms

If you are installing Exchange Server 2016 or 2019 September 2021 or later CU, use the /IAcceptExchangeServerLicenseTerms_DiagnosticDataON or /IAcceptExchangeServerLicenseTerms_DiagnosticDataOFF switch.

For instance,

Setup /m:RecoverServer /IAcceptExchangeServerLicenseTerms_DiagnosticDataON

Note: Make sure to use /TargetDir switch to specify the installation directory.

Restore Custom Settings and Configurations

Once the installation is finished, reboot the server. You can now log in to Exchange Admin Center (EAC) and run PowerShell commands in the Exchange Management Shell (EMS) to restore the SSL certificate and other customizations or configurations in the IIS, Virtual Directory, etc.

Restore Exchange Databases

To restore the database, use the most recent backup. If the backup isn’t available, obsolete, or fails to restore, use an Exchange server recovery software such as Stellar Repair for Exchange. The software can directly extract mailboxes from the database files (EDB files) on the lost server to your newly set up server with complete integrity. All you need to do is enter the admin credentials. Then, the software auto-maps the mailboxes with user accounts and exports the recovered mailboxes to the user’s account on the new server.

To Wrap Up

The article outlines steps that you can follow to rebuild and restore your failed Exchange Server that does not boot after a total loss. However, we highly recommend configuring a minimum of two Exchange Servers and setup a Database Availability Group (DAG) to avoid data loss situations.

DAG, with even two servers, will provide you with at least two copies of the database on different servers and ensure automatic failover protection even if one server fails. In addition, this will give you enough time to restore or rebuild a new server and add it to your existing DAG environment for automatic failover protection against network failure, server failure, or database damage.  

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