Computer system and data management method

A data management method performed by a computer system including a plurality of nodes, wherein

• the computer system includes:
• a host unit that is formed in at least one of the nodes and issues a request of an I/O processing to a predetermined data management unit;
• a plurality of local control units that are formed in a plurality of nodes each including a storage device providing a storage area to the data management unit, and that are each in charge of management of a local logical area based on the storage area of the storage device of each node, respectively;
• and
• a global control unit that is formed in at least one of the nodes,
• the data management method comprising the steps of:
• managing, by the global control unit, a global logical area, based on a plurality of local logical areas allocated to the data management unit that is an I/O processing target of the host unit;
• and
• controlling, by the global control unit, transmission of target data of the I/O processing performed by the host unit with respect to the data management unit, based on a commonality relationship among a first node that is formed with the host unit performing the I/O processing, a second node that is formed with the global control unit, and a third node that is formed with the local control unit managing the local logical area corresponding to the global logical area.