A method of generating in a tertiary storage device a backup copy of data, the method including the steps of writing data to a first set of storage volumes; while data is being written to the first set of storage volumes, mirroring the contents of the first set of storage volumes into a second set of...http://www.google.es/patents/US6035412?utm_source=gb-gplus-sharePatente US6035412 - RDF-based and MMF-based backups
