Geographic Logical Volume Manager (GLVM) provides remote disk mirroring over TCP/IP networks. It is part of the base AIX operating system starting with AIX 5.3 ML3. (It was previously a component of HACMP/XD).
GLVM can help provide a "disaster recovery" strategy by maintaining a realtime copy of the data at a remote disaster recovery site. If the primary site fails, a current copy of the data is available at the backup site. The recovery and reintegration are manual processes, so read the documentation carefully, and test before using in production.
Whitepaper: http://www-03.ibm.com/servers/aix/whitepapers/aix_glvm.pdf