Patent ID: 6961828

Claim:
A cluster system comprising: a plurality of computers; a data storage device; a cluster file system providing exclusive control for maintaining data consistency by using a lock function in order to offer shared access to a file recorded on the data storage device from a process operating on the plurality of computers; means for allocating a memory area in an address space of the process as cluster shared memory and for mapping data of files managed by the cluster file system in the allocated area; means for allocating a cluster shared memory lock corresponding to the lock function of the cluster file system and enabling exclusive read and write access to the mapped data in the shared memory area for maintaining data consistency on the shared memory; access inhibit setting means for inhibiting access to all pages in the allocated shared memory; data accessing means, when accessing an access-inhibited page causes a read page fault, for reading the data mapped to the page from the file recorded on the data storage device and writing the read data on the page; and setting means for read-enabling the page where the data is accessed.