Patent ID: 8250031

Claim:
A computer system for storing data, comprising: a first storage device including a first processor, a first memory and a first volume to store data and a journal volume; a second storage device including a second processor, a second memory, a second volume to copy data from the first volume and a third volume to store data as a snapshot data; wherein the first storage device is configured to store the data and a snapshot request in the journal volume according to an order of arrival if the data is stored in the first storage device as snapshot data, wherein the second storage device is configured to read data from the journal volume asynchronously, to determine whether the data read from the journal volume has the snapshot request, and to store the data stored in the journal volume to the third volume as the snapshot data when the snapshot request is found, wherein the second storage device is configured to identify difference data from a snapshot time at which the snapshot was taken, based on the order of arrival, and wherein data is restored by the difference data and the snapshot data stored in the third volume.