PPRC has been enhanced to include PPRC extended distance (XD). When the PPRC extended distance feature is installed and enabled on the ESS, it provides an alternative to synchronous PPRC. It also adds a new alternative in the ESS-to-ESS data mirroring capabilities. When PPRC extended distance is enabled, updates made to a PPRC primary volume are sent to a secondary volume asynchronously. This helps minimize the impact on application throughput.
When the PPRC extended distance feature is enabled, the primary and recovery storage control sites can be separated by very long distances. Channel extender technology can be used to link the primary and recovery storage control sites. This technology allows these systems to be connected over large distances by using less expensive telecommunication lines, with little performance impact.
Therefore, if your environment has bandwidth restrictions or has extended distance requirements, you might want to consider PPRC extended distance. When operating in extended distance mode, the primary volume sends a periodic, incremental copy of updated tracks to the secondary volume instead of a constant stream of updates. This causes less impact to application writes for primary volumes and less demand for bandwidth resources, while allowing a more flexible use of the available bandwidth. In addition, the lower bandwidth requirement creates the potential for worldwide distance capability when using channel extenders.
The examples that are provided in later sections describe how to use the PPRC extended distance feature when using TSO commands or the ANTRQST API. You can also perform PPRC extended distance-related tasks by using the IBM® TotalStorage ESS Specialist Web interface or the ESS Copy Services command-line interface.
For additional information about performing PPRC extended distance-related tasks, refer to the IBM TotalStorage Enterprise Storage Server® Web Interface User's Guide.