Patent ID: 7664785

Claim:
An information processing system comprising: a plurality of servers each executing an application; a plurality of Wide Area File System (WAFS) clients which are correspondingly connected to said servers; a WAFS server which is connected to said each WAFS client; a storage system, connected to said WAFS server, which stores data for use by the application being executed by said server, said data being stored in a plurality of volumes forming a consistency group; and a backup server, connected to said WAFS server, for controlling backup of the consistency group of said storage system, wherein each WAFS client comprises: a cache for temporarily storing data of files accessed on said storage system, and a cache manager for managing the operation of the cache, wherein said WAFS server comprises: a backup agent that responds to a backup request from said backup server, and a consistency manager that maintains consistency among the caches of the WAFS clients and the consistency group, wherein when said backup server connected to the WAFS server requests said backup agent, included in the WAFS server, to make a backup of a consistency group, said backup agent in the WAFS server requests that said consistency manager in said WAFS server bring to a state of consistency of the data among the caches of said WAFS clients and that the mode of access of the WAFS server by the WAFS client be changed from asynchronous mode to synchronous mode, wherein said consistency manager in WAFS server, in response to said backup agent, requests said cache manager in each WAFS client to flush all dirty data out of said cache and to change mode of access by said WAFS client from the asynchronous mode to a synchronous mode, wherein said cache manager in WAFS client, in response to said consistency manager, flushes all dirty data out of the cache to the WAFS server, and after flushing all dirty data out of the cache, changes the mode of access of the WAFS server by the WAFS client from the asynchronous mode to the synchronous mode, wherein said storage system, in response to a request from said backup agent, makes a snapshot for the consistency group, and wherein said consistency manager in said WAFS server, in response to a request from the backup agent, requests the cache manager in said WAFS client to change the mode of access from the synchronous mode to the asynchronous mode to enable the cache in said WAFS client to operate.