A method for resynchronizing a primary volume in a primary system and a
secondary volume in a secondary system over a network includes, when a
network connection between the primary system and the secondary system is
interrupted, creating a snapshot of the primary volume and determining
data updates transmitted from the primary system to the secondary system
that were not acknowledged by the secondary system. The method further
comprises, when the network connection is reestablished, determining
differences between the snapshot and the primary volume, transmitting the
differences and the unacknowledged data updates from the primary system
to the secondary system, and updating the secondary volume with the
differences and the unacknowledged data, wherein the secondary volume
becomes an updated copy of the primary volume.