Patent ID: 8832395
Filing Date: 2014-09-09
Classification: G06F

Abstract:
1. A storage system which is a main storage system provided with a first storage medium group formed of that is a plurality of first storage media, and a controller having a memory temporarily storing data comprising a prescribed number of subblocks stored in the first storage medium group, and which communicates with a subsidiary storage system having a second storage medium group formed of a plurality of second storage media containing second storage media in which data identical to the data stored in any of the first storage media in the first storage medium group is stored, wherein the controller receives from a higher-level device new data which is data updated from old data that is data stored in any of the first storage media of the first storage medium group and stores the received new data in the memory, reads the old data from the first storage medium group and stores the old data read into the memory, generates transfer data which is data used to replicate in the subsidiary storage system the new data with a quantity of information less than the new data on the basis of a difference between the old data and the new data in the memory, and transmits the transfer data to the subsidiary storage system, reads an old parity which is a parity corresponding to the old data from the first storage medium group and stores in the memory the old parity that has been read, and generates a new parity which is a parity updated from the old parity on the basis of the old parity in the memory and XOR data which is the exclusive logical sum of the new data and old data in the memory and stores the new parity in the first storage medium group, wherein the difference is the XOR data, and the transfer data contains: positional data indicating the position of old subblocks targeted for updating among the plurality of old subblocks that are the plurality of subblocks comprising the old data; and updated data containing new target subblocks which correspond to the old subblocks targeted for updating and which are some of the plurality of new subblocks that are the plurality of subblocks comprising the new data, the controller determines whether or not bit values are all zero for each of the plurality of XOR subblocks which are the plurality of subblocks that comprise the XOR data and generates positional data on the basis of the position of the XOR subblocks for which the bit values are all zero.