Remote Replication Target

The Device-Mapper, as a general purpose mapping subsystem, is part of the Linux kernel since back in the 2.5 development cycle and is shared by applications such as LVM2, dmraid, kpartx, multipathd etc.

Details of any particular mapping (e.g. a mirrored device) are abstracted via pluggable mapping targets (i.e. kernel modules), hence enabling addition of new mappings to a running system.

A new target, the author has been working on since late 2007, is the Replicator Target to cope with disaster recovery requirements in Enterprises. It allows for remote data replication of arbitrary groups of block devices as a single, write-ordered entity to multiple remote sites, supports synchronous and asynchronous replication and fallbehind thresholds to automatically switch from asynchronous to synchronous mode and back, beside other features.