One of EMC’s most widely used product throughout the IT industry for data replication and site failover facility is SRDF (Symmetrix Remote Data Facility).

Companies with business critical customer oriented data always have a requirement for a minimum downtime of the production system and a need for fallback mechanism which should cater this. Technically it is a block by block replication of data disk from the primary site to the secondary fallback site, which caters the purpose of secured customer data incase of a total primary site failure. One of the variant of the SRDF technology which is popular is the Asynchronous mode of transfer of data blocks from primary site to the failover site -SRDF/A. SRDF/A proves very useful when the primary and the secondary sites are located far and the data transmission is through a Interconnect(WAN/MAN). Transmission of data blocks is asynchronous, the writes at the primary site need not wait for the data to be written on the secondary site.