The three-site SRDF/Star-A configuration provides disaster restart capabilities at DC3 or DC4. Figure 4Figure 6 illustrates GDDR operation in the concurrent SRDF/Star-A environment.

Figure 6.               SRDF/STAR-A

The relationship between the DC1 and DC3 sites is maintained through SRDF/Asynchronous replication of primary disk images at DC1 to DC3. An independent SRDF/A relationship is also maintained between DC1 and DC4, with a recovery link in place between DC3 and DC4, which can be activated in case of the loss of DC1 to enable a differential resynchronization between DC3 and DC4.  Both open systems (FBA) and mainframe (CKD) disk images can be replicated.

Figure 6 shows the three GDDR C-Systems with their independent heartbeat communication paths, separate from the production disk and computer facilities.

In this environment, GDDR can perform the following tasks:

• Manage planned site swaps
• Manage recovery after unplanned site swaps
• Perform standard operational tasks:

• IPL, system reset, activate, deactivate
• Trigger stop/start of business workloads

• Actively monitor for unplanned/failure events, including:

• Sites
• Systems
• Loss of SRDF/A
• Inter-site communication failure

• Provide Cyber Recovery from any site or from all sites