PPRC overview
When PPRC is activated, it establishes a mirror between specified volumes on two storage systems. The PPRC mirrored volumes are referred to as a PPRC pair, instance, or as a PPRC-protected volume.
PPRC can mirror data in one of two ways:
- Synchronous mirroring provides concurrent copy over ESCON® links. This is supported by PowerHA® SystemMirror® Enterprise Edition .
Note that ESCON links transmit data in one direction and have distance limitations.
- Non-synchronous mirroring, also called Global Mirror mirroring, provides copying over longer distances. Extended distance mirroring ensures that volumes are consistent with each other at a point-in-time. This method is not supported in PowerHA SystemMirror Enterprise Edition.
Note: FlashCopy® is an
optional feature on the ESS. It is an instant (point-in-time) copy
of the data.
Hardware configuration for PPRC mirroring
The following illustrations show sample hardware configurations that support PPRC-mirroring. The illustrations also show the connections from the ESS to:
- Nodes over SCSI or Fibre Channel connections
- Fibre channel or ESCON links that connect the two ESS systems to mirror data
- The ESS Specialist and ESS Copy Services Specialist over ESSNet
and a wide-area network (WAN) that joins the two ESSNets.
