The three-site SRDF/Star with AutoSwap configuration provides both continuous availability using AutoSwap to DC2 and disaster restart capabilities at DC2 or DC3. Figure 4 illustrates GDDR operation in a concurrent SRDF/Star environment. GDDR can also be configured for operation in a cascaded SRDF/Star environment. SRDF/Star can also be implemented using Consistency Group for z/OS only (without AutoSwap) in a concurrent or cascaded topology which provides disaster restart capability at DC2 or DC3, as depicted in figure 5.

Figure 4.                 
SRDF/STAR with AutoSwap for z/OS

Figure 5. SRDF/STAR with Consistency Group for z/OS

The relationship between the DC1 and DC2 sites is maintained through SRDF/Synchronous replication of primary disk images at DC1 to DC2. Both open systems (FBA) and mainframe (CKD) disk images can be replicated. In a concurrent configuration, the asynchronous relationship is between DC1 and DC3, while in a cascaded environment, the asynchronous relationship is between DC2 and DC3.

In these environments, GDDR can perform the following tasks:

• Manage planned site swaps
• Manage recovery after unplanned site swaps
• Manage reconfiguration of the SRDF/Star environment between concurrent and cascaded topologies
• Manage reconfiguration of the SRDF/Star environment from cascaded to concurrent with a primary processing site move
• Perform standard operational tasks:

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

• Actively monitor for unplanned/failure events, including:

• Sites
• Systems
• AutoSwap event
• ConGroup trip
• Loss of SRDF/S
• Loss of SRDF/A
• Inter-site communication failure

• Provide Cyber Recovery from any site or from all sites