Patent ID: 7769971

Claim:
A computer system comprising: a first storage pool; and a second storage pool; wherein a first backup server of the first storage pool is configured to: convey a first de-duplicated list identifying one or more data segments from the first storage pool to a second backup server associated with the second storage pool; receive from the second backup server a second de-duplicated list identifying at least a subset of the one or more data segments; and convey the subset of the one or more data segments to the second storage pool; wherein each client of one or more clients included in the system is configured to: assemble a batch of data segments including only data segments that do not have a backup copy already stored in the first storage pool; convey the assembled batch to the first backup server; and assign a batch number to the data segments and references in the assembled batch; and wherein the first backup server is further configured to: store batch numbers in a backup history; select only data segments and references for inclusion in the first list whose batch numbers are stored in the backup history; and clear the backup history after conveying said subset to the second storage pool.