Method and computer system for updating data when reference load is balanced by mirroring

A storage system coupled to one or more client computers via a network, comprising:

• a plurality of servers including a first server and a second server, and one or more disk subsystems coupled to the plurality of servers,
• wherein the disk subsystems each have one or more logical devices for storing data written by the client computers,
• wherein the servers each have an interface coupled to the network, a processor coupled to the interface, and a memory coupled to the processor,
• wherein the first server manages, as one or more file systems, data stored in the logical devices,
• wherein the second server manages a second directory tree, which is a replica of a first directory tree corresponding to an entirety or a part of one file system managed by the first server,
• wherein the processor receives, from one of the client computers, via the interface, a request to access a file belonging to the first directory tree or the second directory tree, and judges whether the client computer that has issued the access request has a possibility of issuing at least one of update requests or not,
• wherein the processor selects the first directory tree, when judging that the client computer has a possibility of issuing at least one of update requests,
• wherein the processor selects the second directory tree, when judging that the client computer does not have a possibility of issuing at least one of update requests, and
• wherein, the processor executes access to the selected directory tree as requested, in a case where the selected directory tree is managed by a server to which the processor that has made the selection belongs.

A method of controlling a computer system, the computer system comprising:

• one or more client computers;
• and
• a storage system coupled to the client computers via a network,
• wherein the storage system has a plurality of servers including a first server and a second server, and one or more disk subsystems coupled to the plurality of servers,
• wherein the disk subsystems each have one or more logical devices to store data written by the client computers,
• wherein the servers each have an interface coupled to the network, a processor coupled to the interface, and a memory coupled to the processor,
• wherein the first server manages, as one or more file systems, data stored in the logical devices,
• wherein the second server manages a second directory tree, which is a replica of a first directory tree corresponding to an entirety or a part of one file system that is managed by the first server, the method comprising:
• receiving, by the processor, from one of the client computers, via the interface, a request to access a file belonging to the first directory tree or the second directory tree, and judging, by the processor, whether the client computer that has issued the access request has a possibility of issuing at least one of update requests or not;
• selecting, by the processor, the first directory tree, when judging that the client computer has a possibility of issuing at least one of update requests;
• selecting, by the processor, the second directory tree, when judging that the client computer does not have a possibility of issuing at least one of update requests;
• and
• executing, by the processor, access to the selected directory tree as requested, in a case where the selected directory tree is managed by a server to which the processor that has made the selection belongs.