Chapter 5. Peer-to-Peer Remote Copy
In this chapter we describe the VSE/ESA support for the RVA and the PPRC.
As part of the continuing effort to meet customer requirements for
PPRC standardizes and streamlines today′s disaster recovery data backup capabilities by providing
PPRC provides an RVA synchronous data copying capability for protection against loss of access to data in the event of an outage at the primary site. Updates are sent from the primary RVA directly to the recovery RVA in a cache to cache communication through dedicated ESCON links between the two RVAs. The RVA can be located up to 43 km (26.7 mi) from the host. The primary and secondary volumes must be of the same track geometry.
Figure 19 shows two host systems with an RVA attached to each. The two RVAs are attached on at least one ESCON path. ESCON Directors can be used to extend the distance between the two hosts up to 43 km. The second host is optional if PPRC is being used to migrate data from one RVA to a second within the same data center.
Figure 19. Peer-to-Peer Remote Copy
Both RVAs can treat writes as DASD fast write (DFW) operations. The primary RVA write is handled normally, and it is processed as a cache hit whenever possible; the write to the secondary subsystem is always treated as a write hit. This capability, and the inherent performance capabilities of the RVA, help to mitigate the unavoidable performance impacts of writing the data to both RVAs before signaling the operation as complete to the primary host application.
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