For cluster systems consisting of multiple nodes and shared servers which consist of an on-line and a backup server, we propose a hot-standby scheme of shared servers. In this scheme for shared servers, the shared servers have user data and control data. The on-line shared server sends only the control data to the backup server when it receives an update command. When the on-line shared server fails, the backup shared server reconstructs the shared data by using the latest control data sent from the on-line server and the user data sent from each node. We evaluated the system recovery time and the performance overhead for the hot-standby scheme. This enables the system recovery time to be shortened to 30 seconds and the performance overhead to be reduced to 2%.

For cluster systems consisting of multiple processing nodes and shared servers which consist of an on-line and a backup shared server, we propose a hot-standby scheme for shared servers. In this scheme for shared servers, when the on-line shared server receives a command from a node, it sends only an update command and its data identifier to the backup shared server. Both the on-line and the backup shared server execute the update command independently, and the command result of the on-line shared server is identical to that of the backup shared server. When the on-line shared server fails, the backup reconstructs the shared data by using its own shared data and the user data from each node. We evaluated the system recovery time and the performance overhead for this hot-standby scheme. It enables the performance overhead to be ignored, and the system recovery time to be shortened to 20 seconds in cluster systems.