Computer system capable of fast failover upon failure

摘要

The invention is a computer system capable of fast failover so that a service is stopped only for a brief period of time from a failure in a first site. The computer system includes a primary site for regular operation and a secondary site that operating when the primary site fails. A primary storage (150) and a secondary storage (250) have a synchronization unit () to make contents stored in the primary storage and contents stored in the secondary storage identical to each other. A client (300) has a cache (303) for recording address information (e.g. DNS) that gives the client an access to the server from which the service is provided and information that defines a time to live of the address information. A first server (100) has a primary request log processing unit (101), which instructs the client to shorten the recorded time to live of the address information when communication with the secondary site is detected to be impossible.