EMC SRDF Asynchronous
SRDF/A is an asynchronous copy services solutions, designed to support greater distances between the primary and secondary site, without the response time impact associated with a synchronous solution.
In an SRDF/A solution, the secondary installation will be about 1 minute "behind" the primary installation, and SRDF/A will create subsequent consistent states each about 30 seconds apart. SRDF/A will be used together with business continuance volumes to be able to guarantee a consistent secondary volume.
Asychronous copy services solutions like SRDF/A have no impact on the production systems as long as the link and secondary subsystems are fast enough to offload the information. If the copy process is unable to offload data to the secondary quickly enough, SRDF/A has the ability to throttle host I/O such that it can catch up.
EMC has dedicated a section of their web site to SRDF:
You can also download the SRDF data sheet.
A technical description of SRDF/A can be found in the EMC White Paper Using Remote Replication for Multi-Site Business Continuity.
In our products
IntelliMagic Vision has all the support required to help you assess the required bandwidth for an SRDF/A solution. Specifically, it can assess how much bandwidth can be saved (if any) with a asynchronous solution versus a synchronous solution.
Once SRDF/A is implemented, IntelliMagic Vision can be used to keep track of the bandwidth usage, and also of delay on the primary volumes when cache storage or bandwidth become a bottleneck.