Storage apparatus and method of controlling the same

A storage apparatus comprising a plurality of nodes through which write-data received from a host is written into a disc,

• each of said nodes including:
• a first memory in which said write-data is temporarily stored;
• a second memory as a backup memory for storing said write-data;
• a copier which copies both write-data stored in said first memory and write-data stored in a first memory of another node into said second memory, said copier being able to make communication with a copier of said another node through a copier-interface;
• and
• a processor which controls operation of said storage apparatus,
• wherein when said copier-interface is not troubled, said processor operates in a write-back mode in which said processor informs said host of completion of write-data storage when or after said copier has copied both write-data stored in said first memory and write-data stored in a first memory of another node into said second memory, and then, writes said write-data into said disc, whereas when said copier-interface is troubled, said processor operates in a write-through mode in which said processor writes said write-data stored in said first memory into said disc without copying said write-data into said second memory, and then, informs said host of completion of write-data storage.

A method of controlling a storage apparatus comprising a plurality of nodes through which write-data received from a host is written into a disc, comprising:

• copying, in each of said nodes, both write-data stored in a first memory and write-data stored in a first memory of another node into a second memory;
• judging whether a copier-interface through which each of said nodes can made communication with another node is troubled;
• and
• if said copier-interface is troubled, writing said write-data stored in said first memory into said disc without copying said write-data into said second memory.

A program for causing a computer to carry out a method of controlling a storage apparatus comprising a plurality of nodes through which write-data received from a host is written into a disc, wherein steps executed by said computer in accordance with said program includes:

• copying, in each of said nodes, both write-data stored in a first memory and write-data stored in a first memory of another node into a second memory;
• judging whether a copier-interface through which each of said nodes can made communication with another node is troubled;
• and
• if said copier-interface is troubled, writing said write-data stored in said first memory into said disc without copying said write-data into said second memory.