For DBA’s who are not using the SQL Server Standard Edition double take is one of the best high availability solutions that’s available in the market. Double-Take software gives you the ability to configure a Source and Target machine and choose the directories and folders that you want to replicate from Source to Target. Double-Take uses a delta-replication strategy which only sends the changes since the prior replica. This provides a real-time fast replication of data from one server to the other minimizing the bandwidth. This is a very popular model for pushing data over a WAN.
Below I have organized the screenshots for configuring double take v220.127.116.111.0 to protect SQL Server 2008 R2 SP1.
Hope this helps