Patent ID: 7739465

Claim:
A backup system, comprising: a main storage device for storing original data; a plurality of local storage devices for storing the distributed data of the main storage device; an encoding unit for, after dividing the original data, generating a plurality of encoded data equal to or more than a division number by use of a code of which redundancy is variable; a redundancy control unit for varying the redundancy in the encoding unit; a distribution processing unit for distributing the plurality of encoded data to the plurality of local storage devices and causing the encoded data to be stored in the local storage devices; and a restoring unit for retrieving the encoded data corresponding to at least the division number of the original data from the local storage devices and restoring the original data; wherein the encoding unit includes: a block dividing unit for dividing the original data into n-units of block data, and an encoded data generating unit for generating, merely in a number m according to redundancy Q, headers, in each of which a bitmap specifying one or a plurality of blocks for obtaining exclusive OR in the n-units of block data is disposed, and encoded data comprised of exclusive OR data of the one or plurality of block data specified by the header; wherein the restoring unit retrieves the block number n or more of the encoded data from the plurality of local storage devices, and converts the header into a unit matrix by means of the Gaussian elimination method so as to restore the n-units of block data.