Exchange Datacenter Switchback

Generally, datacenter failures are either temporary or permanent. With a permanent failure, such as an event that has caused the permanent destruction of a primary datacenter, there’s no expectation that the primary datacenter will be activated. However, with a temporary failure (for example, an extended power loss or extensive but repairable damage), there’s an expectation that the primary datacenter will eventually be restored to full service.

The process of restoring service to a previously failed datacenter is referred to as a switchback. The steps used to perform a datacenter switchback are similar to the steps used to perform a datacenter switchover

It’s important that switchback not be performed until the infrastructure dependencies for Exchange have been reactivated, are functioning and stable, and have been validated. If these dependencies aren’t available or healthy, it’s likely that the switchback process will cause a longer than necessary outage, and the process could fail altogether.

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Exchange Datacenter Switchover

A switchover is a manual process in which an administrator manually activates one or more mailbox database copies. Switchovers, which can occur at the database or server level, are typically performed as part of preparation for maintenance activities. Switchover management involves performing database or server switchovers as needed.

For example, if you need to perform maintenance on a Mailbox server in a DAG, you would first perform a server switchover so that the server didn’t host any active mailbox database copies.

There are four basic steps that you complete to perform a datacenter switchover, after making the initial decision to activate the second datacenter:

  1. Terminate a partially running datacenter
  2. Validate and confirm the prerequisites for the second datacenter
  3. Activate the Mailbox servers
  4. Activate the Client Access servers

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