Choosing a coupled XRC configuration

With CXRC, you can choose to use the SDM to manage your coupled data sets at the recovery site, at the primary site, or on a remote host apart from the application host.

Figure 1 shows a coupled XRC configuration with the system data mover at the recovery location. Figure 2 shows a coupled XRC configuration with the system data mover at the primary site. Figure 3 shows a coupled XRC configuration with the system data mover located at the primary site but on a remote host apart from the primary host system itself.

Figure 1. CXRC configuration with system data mover at recovery site

CXRC configuration with system data mover at recovery site. At the primary site, three sets of primary systems and primary volumes. At the recovery site, three sets of data mover, recovery system, journal control and secondary volumes.

Locating the system data mover at the recovery site is the most viable scenario for effective disaster recovery, as shown in Figure 1. Because the system data mover is not at the primary site, it is protected from any disasters that might negatively impact the primary site, such as floods, storms, fires, earthquakes, bombs, or other accidental or intentional catastrophes. To determine the location of the recovery site, consider the types of disasters that you want to protect your installation's data against. For example, if hurricanes are common in your area, you might want to establish the recovery site at a sufficiently remote location, perhaps 50–100 miles away from the primary site. The flooding and power outages that accompany a hurricane, which might adversely affect your primary site, would be unlikely to affect your remote recovery site.

Figure 2. CXRC configuration with system data mover at primary site

CXRC configuration with system data mover at primary site. At the primary site, three sets of primary systems, data movers and primary volumes. At the recovery site, three sets of journal control, secondary volumes and recovery systems.

You may choose to locate the system data mover on the primary host system at the primary site, with the recovery host system located remotely from the primary system, as depicted in Figure 2. However, this is the least effective and most vulnerable scenario for disaster recovery. If your application host goes down, the system data mover will be unavailable for copy operations to the recovery site. This scenario might be acceptable for short-term testing purposes only.

Figure 3. CXRC configuration with system data mover at primary site on remote host

CXRC configuration with system data mover at primary site on remote host. At the primary site, three sets of primary systems and primary volumes, with the data movers on remote hosts. At the recovery site, three sets of journal control, secondary volumes and recovery systems.

Locating the system data mover on a remote, separate host at the primary site is an option for configuring your CXRC environment, as shown in Figure 3. There is a certain measure of safety built into having your SDM located on a separate host from your primary system, even if the hosts are at the same site. You run the risk, however, of the same disasters impacting the remote recovery host that affect the primary application host. This option is valid for early CXRC configuration testing or for special testing at any time.