Storage system and path management method

A storage system configured to maintain uninterrupted remote-copy replication when a second storage node at a secondary site is dynamically increased or decreased, the system comprising:

• one or a plurality of first storage nodes installed at a primary site;
• a plurality of second storage nodes installed at the secondary site;
• and
• a first management device,
• wherein
• (a) each first storage node is provided with a primary volume that a host device can read from and write to,
• (b) each second storage node is provided with a secondary volume that backs up data written to the corresponding primary volume, and
• (c) for every pair of corresponding primary and secondary volumes a remote copy path is set between the first storage node and the second storage node that hosts the secondary volume, the remote copy path including first and second physical routes whose addressing information is stored in a path-management table,
• wherein in response to movement of the secondary volume triggered by increase or decrease of a second storage node, the first management device:
• (i) collects, before replication is suspended, port-address information of the first storage node that owns the corresponding primary volume and port-address information of a destination second storage node that will host the moved secondary volume,
• (ii) establishes, using the collected port-address information, a new remote copy path between the first storage node and the destination second storage node, stores the new port-address information in the path-management table, and resumes remote copying over the new path, and
• (iii) after successful resumption of remote copying, deletes from the path-management table the port-address information that defined an original remote copy path between the first storage node and a source second storage node that previously hosted the secondary volume, thereby preventing continued use of the obsolete path.