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Application failover

If you have not done so already, launch the Double-Take Availability Application Manager by selecting Start, Programs, Double-Take, Availability, Double-Take Availability Application Manager.

There are two options for how to perform failover:

If you are using a standalone BlackBerry server with Exchange or SQL, there are additional steps so that the BlackBerry server will recognize when the server that has the BESAdmin account has been failed over

If an error occurs during failover, a message box will appear. You can use the Actions menu to launch the failover log file.

Note:
  • If you open the Application Manager and try to select a source that is currently down, a prompt will appear stating that the source was not available and that if the source is failed over, you should first select the target. If you select the target, then select the source (as recommended in the prompt), the same prompt appears (though you would expect to get a prompt to failover).
  • You cannot use the Application Manager to failover until a failover condition has been met in accordance with the failover monitor settings set when you configured protection.
  • In a clustered failover scenario where the source suddenly becomes unavailable (crashes), if the Application Manager is open, it may appear to "hang" or pause for up to 30 minutes before the process will continue. This is caused by the Application Manager waiting on the msclus.dll to respond. To reduce the amount of time before failover can continue, close, then re-open the Application Manager interface.
  • If you are using Outlook Web Access or Outlook 2007, after failover a security alert is displayed. This is because the certificate has the source server name but is now on the target. Click Allow or OK to dismiss the alert.
  • If an Exchange 2007 environment has more than one domain controller and the domain controller that Exchange is using changes during the failover process, stores may not mount during failover. To work around this issue, either modify the failover script to use the domain controller that Exchange uses when the Information Store service is started; or, mount the stores manually and run the Replace replicas PowerShell call from the failover script to update the PF replicas (if applicable).
  • After failover, linked databases in the SQL instance will be unavailable until the service master key is updated. After failover, you will need to run the command “alter service master key force regenerate” against the SQL target server to reset the service master key, then remove and re-add the linked servers into the target SQL instance.
  • In SQL Server Database-only mode, after failover with snapshot is finished the SQL Server services on the target server are stopped and the databases are not mounted. You will need to manually start the MSSQLServer service for each instance on the target server, then manually attach the databases.
  • After failing over in a SQL Workgroup (no DNS), you will not be able to connect to the source server instance of SQL. You can work around this issue by creating an alias on the target with the source server’s name.
  • After failing over a SQL 2008 source to a SQL 2008 target, Rich Internet Applications created using ADO.net 2 may not connect.