Storage unit, storage unit control method, and storage system

A method of controlling a disk array system connected communicably to a plurality of other disk array systems each having a plurality of first hard disk drives on which data is stored, said disk array system having a plurality of second hard disk drives on which data is stored, wherein each of said plurality of other disk array systems is arranged to receive and store data from a different respective information processing unit in response to commands received therefrom, each said information processing unit writing and reading said data to and from said corresponding one of said plurality of other disk array systems, said method comprising the steps of:

• receiving, in a second storage controller of said disk array system, copies of first storage data and first identifiers from a first storage controller of each of said other disk array systems, respectively, said first storage data being stored in a plurality of first storage blocks created by logically partitioning a data storage area of said plurality of first hard disk drives, said first identifiers identifying the first storage blocks;
• calculating, in said second storage controller, an exclusive OR of the copies of the first storage data, with a correspondence established among the first identifiers, from the copies of the first storage data received from said other disk array systems;
• and
• storing, by said second storage controller, a calculation result of the exclusive OR into second storage blocks of said second hard disk drives, said second storage blocks of said second hard disk drives having second identifiers corresponding to the first identifiers, said second identifiers individually identifying said second storage blocks, and said second storage blocks being created by logically partitioning a data storage area of said plurality of second hard disk drives such that the second storage blocks have a block length equal to the block length of the first storage blocks;
• wherein the first identifiers include first block numbers identifying said first storage blocks in corresponding ones of said other disk array systems, said second identifiers include second block numbers identifying said second storage blocks in said disk array system, and said first block numbers are identical to said second block numbers for corresponding first and second identifiers for all of said disk array system and other disk array systems.

A disk array system comprising a plurality of first disk array systems each having a first storage controller and a plurality of first hard disk drives on which data is stored;

• and a second disk array system connected communicably to the first disk array systems and having a second storage controller and a plurality of second hard disk drives on which data is stored, wherein each of said first disk array systems is arranged to receive and store data from a different respective information processing unit in response to commands received therefrom, each said information processing unit writing and reading said data to and from said corresponding disk array system,
• wherein in each of said first disk array systems:
• said first storage controller sends a copy of first storage data and first identifiers to said second disk array system, said first storage data being stored in a plurality of first storage blocks created by logically partitioning a data storage area of said plurality of first hard disk drives, said first identifiers identifying the first storage blocks, and
• wherein in said second disk array system, said second storage controller comprises:
• a first data receiving unit that receives copies of the first storage data and the first identifiers from said first disk array systems;
• a first data operation controller that calculates an exclusive OR of the copies of the first storage data, with a correspondence established among the first identifiers, from the copies of the first storage data received by said first receiving unit from said first disk array systems;
• and
• a first disk controller that stores a calculation result of the exclusive OR, calculated by said first data operation controller, into second storage blocks of said second hard disk drives, said second storage blocks of said second hard disk drives having second identifiers corresponding to the first identifiers, said second identifiers individually identifying said second storage blocks, and said second storage blocks being created by logically partitioning a data storage area of said plurality of second hard disk drives such that the second storage blocks have a block length equal to the block length of the first storage blocks,
• wherein the first identifiers include first block numbers identifying said first storage blocks in corresponding ones of said other disk array systems, said second identifiers include second block numbers identifying said second storage blocks in said disk array system, and said first block numbers are identical to said second block numbers for corresponding first and second identifiers for all of said disk array system and other disk array systems.