This has also been added to the Westcoast Solutions Team FAQ
Synchronous Replication
This method does not allow an update to the primary data to until it has been updated at the 2nd location. This has an obvious performance impact due to the transfer and confirmation the data has been written. Using Synchronous Replication is not advised over long distances.
With Synchronous Replication you are not fully protected against data loss in the event of a disaster as the update may not have completed at one of the sites when the disaster had occurred.
Asynchronous Replication
This method of replication is proving to be more and more popular due to the fact Asynchronous Replication is not limited to distance. The Data in an Asynchronous solution is immediately marked as complete to the application using the data, and then it is copied to the remote site.
Regards
Technical ISS Solutions Team
