Patent ID: 7325111

Claim:
A system for mirroring an active file system of a primary server to one or more destinations in a distributed storage system environment, the system comprising: a volume of the primary server, the volume having one or more data blocks; a snapshot manager running on the primary server configured to create one or more snapshots of the active file system, with each data block in a snapshot being owned by the oldest snapshot in which it appeared; and a mirroring application running on the primary server, said mirroring application configuring a sender module associated with each destination, said sender module configured to query its destination for information about a reference snapshot for that destination, and said mirroring application also configuring a scanner to register each snapshot of which it is notified by each sender and to find the oldest snapshot in a group of destinations in a mirror process, and assigning a logical age to each snapshot, said scanner being further configured to scan said volume to inspect its data blocks, and to select data blocks that are newer than the oldest reference snapshot in the group and to tag those blocks with a logical age corresponding with the age of the snapshot that owns that data block.