US Patent 9459804 Active replication switch

A method, system, and computer program product for replication comprising allowing a subset of sites, wherein the sites comprise a first site, a second site and a third site and further wherein each site has a volume, to have active/active VSL replication, which presents two volumes at two different sites as a single volume, and another set of the sites to have a volume which is a replications of the volume presented by the VSL, and enabling the system to transparently shift which subset of the sites are replicated by the VSL and which sites are replications of the volume presented by the VSL; where the replication of the VSL is performed by a second replication technique.