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GDPS, or Geographically Dispersed Parallel Sysplex, is a family of service offerings from IBM that manages disk and tape mirroring and works to speed the recovery of applications on the z/OS environment. There are several versions of GDPS available, each of which is based upon a DASD mirroring technology.
PPRC, or Peer to Peer remote copy, from IBM is one of these DASD mirroring technologies. PPRC provides synchronous data mirroring between two separate DASD subsystems, primary and secondary, that are connected by a fiber link. WRITES to logical volumes within the primary DASD subsystem are replicated synchronously on the secondary DASD subsystem. Synchronously, in this instance, means that the WRITE IO to the primary subsystem does not complete until the secondary subsystem notifies the primary subsystem that the replication is complete. This process is transparent to the applications and ensures that the data on the primary and secondary subsystems is always consistent. Given this, in the event of a disaster, it should be possible to switch from the primary to the secondary DASD subsystem and continue processing without needing to restore any data. PPRC, like other DASD mirroring technologies, provides commands to perform this switch.
However, although PPRC provides data consistency and provides commands to switch between DASD subsystems, a switch is still a disruptive process that may take hours to complete.
HyperSwap, also a service offering from IBM, is a set of automation scripts built upon GDPS/PPRC that aims to quickly swap a large number of PPRC volume pairs and do it without restarting systems.
HyperSwap requires that all hardware RESERVES directed against PPRC enabled volumes be converted to global ENQs. Because of this requirement, HyperSwap has code that attempts to validate that the shared DASD complex is configured to convert all RESERVES by default. With GDPS/PPRC 3.1 APAR AG31C38, HyperSwap code calls theVPCEXIT4 REXX EXEC, which validates that all necessary RESERVES are converted to global ENQs and then returns the answer to the HyperSwap code.
CA MII uses this interface to provide the support necessary to run GDPS/PPRC HyperSwap with CA MII. There are two parts to this support supplied with CA MIM:
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