Patent ID: 8645648

Claim:
A method for performing volume replication for allowing a destination volume to be synchronized (sync) with a source volume, the method comprising: allocating a first entry in a volume log table (VLT) of the source volume, and initializing a plurality of fields of the first entry comprising: setting a sequence number (SeqNum) defined in a first field of the first entry to an initial setting value; and setting an operation code (OpCod) defined in a second field of the first entry to an operation code representing a state of the source volume; wherein the initial setting value recorded in the first field of the first entry is further assigned to a first variable; allocating a second entry in a VLT of the destination volume, and initializing a plurality of fields of the second entry comprising: setting an OpCod defined in a second field of the second entry to an operation code representing a state of the destination volume; adding an increment to a value of a master sequence number variable of the destination volume, and copying the value of the master sequence number variable of the destination volume into a first field of the second entry in the VLT of the destination volume as a SeqNum defined therein, and into a fourth field of the first entry in the VLT of the source volume as an alternative volume's sequence number (AltVolSN) defined therein, wherein the value of the master sequence number variable of the destination volume is further assigned to a second variable; setting a fourth field of the second entry in the VLT of the destination volume as a starting address, wherein the fourth field of the second entry is used for recording an index of a next data block to be synchronously replicated (DstVLT.NxtSynBlk); and performing a background copy (Background Copy of Source to Destination) procedure started from the starting address for copying the source volume to the destination volume.