US Patent 10082980 Migration of snapshot in replication system using a log

In one aspect, a method includes copying an oldest snapshot of a first volume of a first storage array to a second volume of a second storage array and copying a log to the second storage array to form a replica log. The log includes write I/Os applied to the first volume and bookmarks denoting when snapshots of the first volume are generated. The method further includes generating a first snapshot of the second volume, applying data from the replica log to the second volume until a bookmark is reached and generating a second snapshot of the second volume after the bookmark is reached. The first snapshot is a copy of the oldest snapshot.