Asynchronous Replication from a secondary to a tertiary target allows a replication target to be used as a source for another replication (the tertiary target). Its file systems can also be browsed in a read-only state and be replicated to the tertiary target.
Benefits of Asynchronous Replication
This feature has the benefit of performing replications to a remote target via a WAN link without making heavy demands on the resources of the main server. Asynchronous Replication can offload the network demands of the slower WAN link away from the main server. Typically, replications done over a WAN link can cause frequent interruptions to the main read/write server and tax its resources. In fact, backing up larger file systems to a remote target over a WAN link can take hours and make heavy demands on the main server's resources. In Asynchronous Replication, however, a chain is created wherein the backup from the main server to the initial target (called the secondary target) is completed first. Then, the backed up data from the secondary target is replicated via a WAN link to the tertiary target, without making frequent demands on the CPU of the main read/write server. With fewer resource demands on the main server it is possible to replicate to the secondary target more often than to the tertiary replica.