SRDF Star

SRDF/Star is a three-site disaster recovery solution that consists of the primary (production), secondary, and the tertiary site.

 

Benefits
SRDF/Star provides the following features and benefits:

  • The ability to maintain protection and business continuance despite the loss of any site in a three-site topology (primary, secondary, tertiary).
  • The ability to resume asynchronous protection between the secondary and tertiary sites, with minimal data movement, in the event of a primary site failure.
  • EMC host-based SRDF software support for control functions.


SRDF/Star control for open systems
You can use Solutions Enabler software to control, manage, and automate the SRDF/Star processes at the production site through the symstar command. Session management is required at Symmetrix A. The host software and Enginuity maintain the information needed to perform the differential synchronization between Symmetrix B and C.

Host-based automation is provided for normal, transient fault, unplanned failover (switch), and planned failover operations. This automation is delivered in Solutions Enabler with the SRDF/Star license.

Concurrent SRDF/Star
In concurrent SRDF/Star operations, Symmetrix B serves as the secondary site and the target of the SRDF/S links from Symmetrix A. Symmetrix C serves as the tertiary site and the secondary site of the SRDF/A links from Symmetrix A. The recovery links are the SRDF/A links between Symmetrix C and Symmetrix B.

Cascaded SRDF/Star
Cascaded SRDF/Star enhances the basic cascaded SRDF functionality by using the SRDF/Star differential resynchronization.

 
Concurrent SRDF/Star with R22 devices
SRDF supports concurrent SRDF/Star topologies using concurrent R22 devices. R22 devices have two SRDF mirrors, only one of which is allowed to be active on the SRDF links at a given time.

R22 devices simplify SRDF/Star failover situations, improve the resiliency of the SRDF/Star application, and reduce the number of steps involved in failover procedures.