Exchange 2010 includes a feature called Datacenter Activation Coordination (DAC) mode that is designed to prevent split brain at the database level during switchback procedures that are being performed after a datacenter switchover has occurred. One of the side benefits of enabling DAC mode is that it enables you to use the built-in recovery cmdlets to perform the datacenter switchover and switchback.
In the real world, there are several different factors that determine what commands to run and when to run them. For example:
- Are Exchange Servers available in the primary datacenter?
- Is network connectivity available between the primary and remote datacenter?
- Is Exchange deployed in a topology with a single Active Directory site or multiple sites?
The answers to these questions determine not only the specific commands to run but also where the commands should be run.
In addition, administrators need to understand what the desired outcomes of those commands are. For example:
- How do I verify that stop-databaseavailability group was successful?
- How do I verify that restore-databaseavailabilitygroup performed the correct steps?
- When is it appropriate to run start-databaseavailailitygroup?
Each of these requires a different set of verification steps before proceeding.
And of course as with any process there are those occasional expected errors.
With this in mind, I want to introduce the Datacenter Switchover Tool, a kiosk-based PowerPoint application that allows administrators to work through the flow of questions to determine:
- What commands to run and where to run them
- How to verify the commands completed successfully.
- How to walk through a Datacenter Switchover from the Mailbox server / database availability group perspective.
To use the tool, simply download it and open it in PowerPoint. Make sure use only the buttons that are available on the screen. The tool will walk you through the correct questions, in the correct order, and provide feedback on the commands to execute and their verification.
The location of the tool is here: http://gallery.technet.microsoft.com/Exchange-2010-Datacenter-09a81fc6
Note: We have now also published the Exchange Server 2010 DAG Switchover GWT (Guided Walkthrough). You can use that as an additional resource to help you get through the switchover process.