A storage system maintains a journal of journal entries and at lease one snapshot of one or more data volumes. By assigning a unique sequence number to journal and snapshot, it is easy to find a journal which can be applied to the snapshot. A technique is described for detecting an overflow condition...http://www.google.de/patents/US20060190692?utm_source=gb-gplus-sharePatent US20060190692 - Method and apparatus for backup and recovery using storage based journaling
