In a computer system 10 that includes multiple nodes 100 capable of storing data, and a management computer 410 that manages the nodes 100, a first volume of a first node and a second volume of a second node 100 constitute an HA (High Availability) pair for managing identical data in a duplicated manner. the CPU 120 of the second node is configured to, When the first node becomes offline, write data that is to be written into the second volume of the second node thereafter is written into the second volume and into a third volume of a third node that is different from the first node and the second node.