Patent ID: 7761737

Claim:
A server that provides service, comprising: a storage unit that stores data including operating system data; a virtual RAM disk; a disk drive unit upon receiving a swap out request, that freezes access to the storage unit, generates an operating system snap shot minimally required to operate an operating system operated by the server based on the operating system data stored in the storage unit, migrates the operating system snap shot to another server, and stores the operating system snap shot in the virtual RAM disk; a snap shot storing unit; and a saving processing unit that stores the operating system snap shot stored in the virtual RAM disk and the data in the storage unit to which access has been frozen, together as a snap shot, into the snap shot storing unit, wherein when the disk drive unit receives from the another server a request for a page corresponding to a page fault that occurs as the another server, based on the operating system snap shot migrated from the server, provides the service that has been provided by the server, the disk drive unit migrates the page from the server to the another server.