Methods, apparatus and computer program products implement embodiments of the present invention that include defining a source data volume including a first multiple of source snapshots, and storing the first multiple of the source snapshots in a first storage pool including a second multiple of storage regions having respective identifiers. Upon receiving a request to copy the source data volume to a target data volume in a second storage pool, a first given source snapshot including a first set of the storage regions is accessed, and a second given source snapshot preceding the first given source snapshot is identified, the second given source snapshot including a second set of the storage regions. A set difference of the second and the first sets of the storage regions is identified, respective identifiers of the set difference are stored to the target volume, and a target snapshot is created for the target volume.