Storage system

A storage system comprising:

• a plurality of nodes, each of which includes a processor and a drive;
• and
• a management unit,
• wherein each of the nodes stores data in the drive, receives data write and read requests, and writes and reads the data stored in the drive of its own node;
• wherein the plurality of nodes generate parity based on a plurality of pieces of data stored in different nodes, store the parity in a drive of a node different from the plurality of nodes, and form a stripe from the plurality of pieces of data and the parity generated based on the plurality of pieces of data;
• wherein when a node is added or reduced, the management unit transmits an arrangement change request to the plurality of nodes, and
• wherein according to the arrangement change request, the plurality of nodes perform reconfiguration of the stripe stored in the node which is not added or reduced, by changing a combination of data constituting the strip and generating parity based on the data stored in the added or reduced node and the data stored in the node which is not added or reduced.

A configuration change method for a storage system including:

• a plurality of nodes, each of which includes a processor and a drive;
• and
• a management unit;
• the configuration change method comprising:
• storing, by each of the nodes, data in the drive;
• receiving, by each of the nodes, data write and read requests and writing and reading the data stored in the drive of its own node;
• generating, by the plurality of nodes, parity based on a plurality of pieces of data stored in different nodes and storing the parity in a drive of a node different from the plurality of nodes;
• forming, by the plurality of nodes, a stripe from the plurality of pieces of data and the parity generated based on the plurality of pieces of data;
• when a node is added or reduced, transmitting, by the management unit, an arrangement change request to the plurality of nodes;
• moving, by the plurality of nodes according to the arrangement change request, the parity, which is generated based on the data, between a node which is not added or reduced, and the added or reduced node without moving the data;
• and
• performing, by the plurality of nodes according to the arrangement change request, reconfiguration of the stripe stored in the node which is not added or reduced, by changing a combination of the data constituting the strip and generating parity based on the data stored in the added or reduced node and the data stored in the node which is not added or reduced.