Patent ID: 8364920

Claim:
A method of transferring a backing lun (logical unit number) and a lun clone of the backing lun from a first volume of a primary server computer (“primary server”) to a second volume of a secondary server computer (“secondary server”), the first and second volumes each storing data of an active filesystem and snapshots of the active filesystem of each server, the backing lun and the lun clone sharing a plurality of shared data blocks within the first volume, the backing lun and the lun clone each also including separate data blocks in the first volume which are not shared, the method comprising: generating the lun clone on the primary server from a first snapshot of the active filesystem of the first volume which includes the backing lun; creating a second snapshot of the active filesystem of the first volume which includes the shared data blocks and the separate data blocks of the lun clone; transferring the first and second snapshots from the primary server to the secondary server; creating a new backing lun in the active filesystem of the second volume from the shared data blocks and the separate data blocks of the backing lun in the transferred first snapshot; creating a third snapshot of the active filesystem of the second volume which includes the new backing lun; creating a new lun clone in the active filesystem of the second volume from the new backing lun of the third snapshot; updating the new lun clone with the separate data blocks of the lun clone in the transferred second snapshot; and wherein: the new lun clone and the new backing lun of the second volume share copies of the same plurality of data blocks as are shared by in backing lun and the lun clone in the first volume.