A source storage server receives various write requests from a set of
clients, logs each request in local memory, and forwards each log entry
to a destination storage server at a secondary site. At a consistency
point, the source storage server saves data, modified per the requests,
to a first set of mass storage devices, and also initiates a
synchronization phase during which process the modified data is mirrored
at the secondary site. The destination storage server uses data in the
received log entries to mirror at least a portion of the modified data in
a second set of mass storage devices located at the secondary site, such
that said portion of the modified data does not have to be sent from the
source storage server to the destination storage server at the
consistency point.