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The SRDF/Star disaster recovery solution provides advanced multisite business continuity protection for enterprise environments. It combines the power of Symmetrix Remote Data Facility (SRDF) synchronous and asynchronous replication, enabling the most advanced 3-site business continuity solution available today.
SRDF/Star enables concurrent SRDF/S and SRDF/A operations from the same source volumes. It provides the ability to incrementally establish an SRDF/A session between the two remote sites if a primary site outage occurs. This capability is available only through SRDF/Star software.
This capability takes the promise of concurrent synchronous and asynchronous operations (from the same source device) to its logical conclusion. If a primary site failure occurs, SRDF/Star allows you to quickly reestablish protection between the two remote sites. You can then restore the primary site when conditions permit as quickly.
With SRDF/Star, enterprises can quickly resynchronize the SRDF/S and SRDF/A copies by replicating only the differences between the sessions. Doing so-allows for faster resumption of protected services after a source site failure.
Note: SRDF/Metro does not support SRDF/Star configurations, rather it supports SRDF/Metro Smart DR.
Concurrent SRDF allows the same source data to be copied concurrently to PowerMax arrays at two remote locations. As Figure 182 shows, the capability of a concurrent R1 device to have one of its links synchronous and the other asynchronous is also supported as an SRDF/Star topology. Also, SRDF/Star allows the reconfiguration between concurrent and cascaded modes dynamically.
Note: SRDF/Metro supports 3-site Concurrent SRDF.
Cascaded SRDF allows a device to be both a synchronous target (R2) and an asynchronous source (R1) creating an R21 device type. SRDF/Star supports the cascaded topology and allows the dynamic reconfiguration between cascaded and concurrent modes. See Figure 183 for a representation of the configuration.