Asynchronous replication is a "store and foreward" approach to data backup.
Asynchronous replication writes data to the primary storage array first and then, depending on the implementation approach, commits data to be replicated to memory or a disk-based journal. It then copies the data in real-time or at scheduled intervals to replication targets.
Unlike synchronous replication, asynchronous replication is designed to work over long distances. It does not require as much bandwidth as synchronous replication and can tolerate some degradation in connectivity.
See also: cloud backup