(1) In communications, the system that issues a request to establish communications with another system.
(2) In distributed data management (DDM), a system containing an application program that requests access to data in another system.
(3) The system that sends information in a network of systems that exchange objects and data. See also target system.
(4) The system that currently owns the production copy of an independent disk pool in a cross-site mirroring (XSM) environment. Changes to the production copy of an independent disk pool are replicated to all mirror copies of the independent disk pool that exist on backup nodes within the recovery domain.