Overview of extended remote copy (XRC)

Extended remote copy is a combined hardware and software solution to the problem of accurate and rapid disaster recovery. XRC also provides a DASD and workload migration solution.

XRC is designed for sites that match the following criteria:
  • Must maintain the highest levels of performance on their primary system.
  • Support extended distances between volume copies.
  • Can support a recovery point objective time of a few seconds.
  • Provides support for a mixed vendor environment. You are allowed to mix and match primary and secondary volumes for any vendor supporting XRC architecture. Primary volumes must have XRC architecture support, but secondary volumes need not have XRC architecture support.

Protecting your enterprise’s data requires that related updates are applied to the secondary volumes in the same order as they were applied on the primary volumes. Maintaining data integrity becomes especially critical when a volume is updated by multiple applications, or when a data set exists on multiple volumes spread across multiple storage controls. XRC’s design strategy ensures that secondary updates are applied on a consistent basis across multiple storage controls. This update sequencing is necessary in order to avoid data integrity problems and potential data loss.

XRC supports channel extenders, ESCON, FICON®, and parallel channel operation. With ESCON and FICON channels, the XRC function provides for the recovery system to reside at an extended distance from the primary system.

Figure 1 presents an overview of the XRC option of remote copy. The workload (or DASD) migration configuration is basically the same, except that the recovery site would be considered the migration target.

Figure 1. Extended remote copy overview
Extended remote copy overview. The primary site consists of primary systems, storage control and primary volumes. The recovery (target) site consists of primary systems, storage control and secondary volumes.