Patent ID: 8583884

Claim:
A computing system comprising a first storage system and a second storage system and which backs up data written from a host into a first logical volume in the first storage system to a third logical volume in the second storage system, wherein the first storage system comprises: a first copy monitoring/control unit for copying data written into the first logical volume in the first storage system to a second logical volume in the first storage system according to a copy request from the host; and a second copy monitoring/control unit for creating a journal, including the data which was copied to the second logical volume, as update history information of the first logical volume from the data which was copied to the second logical volume, storing the journal in a journal volume in the first storage system, and transferring to the second storage system the journal containing the data, which was created from the data copied to the second logical volume, asynchronously with the writing of other data from the host into the first logical volume; and a first difference bitmap for managing the copying of data from the first logical volume to the second logical volume, and creating the journal from second logical volume, wherein the first copy monitoring/control unit sets each bit of the first difference bitmap corresponding to each unit area of the second logical volume which stores data copied from the first logical volume to a first status to indicate the unit areas of the second logical volume which are copy targets for the second storage system according to the copy request from the host, wherein the second copy monitoring/control unit creates, in the journal volume, the journal for areas in the second logical volume corresponding to the bits set in the first difference bitmap after the data written into the first logical volume is copied to the second logical volume, and wherein the second storage system comprises: a third copy monitoring/control unit for writing the data which was transferred from the first storage system into the third logical volume.