ABSTRACT
Asynchronous replication establishes a remote mirror from one location to another. Any time the primary system encounters a write, the replication kicks in and writes that same data to another system. The subtlety is that asynchronous replication allows the primary write operation to complete, and then allows the write to the target or redundant system a little later. The corner case failure mode is if the primary write fails prior to replication on the target within that first minute. This corner case can be remedied by having paper backup of that information. There are applications, such as stock trading, where this is not an acceptable scenario, so that is the time to use synchronous replication. But for applications such as patient records, asynchronous mirroring is a workhorse.
