A peer-to-peer backup storage system automatically switches from a primary storage site to a mirrored backup site in response to a primary site failure, where the secondary site then honors any existing host initiated reservation of primary storage. Each site includes a storage controller and storage,...http://www.google.de/patents/US6304980?utm_source=gb-gplus-sharePatent US6304980 - Peer-to-peer backup system with failure-triggered device switching honoring reservation of primary device
