Jehan-Francois Paris. Using volatile witnesses to extend the applicability of available copy protocols. In Proceedings of the Second Workshop on Management of Replicated Data. IEEE, November 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....reading and writing of the stored 5 view entries (file version and replica id) of an entity. This operation requires coordinating the accesses of a complex entity. In a distributed entity, the view entry may exist separately from the components of the entity. As an example, volatile witnesses [11] can be used for storing and accessing the viewentries. These witnesses would be placed so that they are more available than the individual components of the entity. ffl Replica selection is done while maintaining view consistency, and it must be efficient since it lies in the critical path of ....

Jehan-Francois Paris. Using volatile witnesses to extend the applicability of available copy protocols. In Proceedings of the Second Workshop on Management of Replicated Data. IEEE, November 1992.

....active primary sites. When the system has multiple backups, the sites vote to select the valid primary. However, when the service includes only two sites, communication failures may cause each server to assume the other has failed. In this situation, the service may include a third party witness [24] to select the primary site. This witness does not act as a primary or backup server, but casts the deciding vote in failure diagnosis. In a realtime control system, the actuator devices could implicitly serve as this witness; if a new server starts issuing commands to the actuators, the devices ....

J.-F. Paris, "Using volatile witnesses to extend the applicability of available copy protocols," in Proc. Workshop on the Management of Replicated Data, pp. 30--33, November 1992.

....in multiple active primary sites. When the system has multiple backups, the replicas can vote to select a single, valid primary. However, when the service has only two sites, communication failures can cause each site to assume the other has failed. In this situation, a third party witness [27] can select the primary site. This witness does not act as a primary or backup server, but casts the deciding vote in failure diagnosis. In a real time control system, the actuator devices could implicitly serve as this witness; if a new server starts issuing commands to the actuators, the devices ....

J.-F. Paris, "Using volatile witnesses to extend the applicability of available copy protocols," in Proc. Workshop on the Management of Replicated Data, pp. 30--33, November 1992.

....through missed update messages, lost or delayed messages could trigger false failure detection, resulting in multiple active primary sites. When the system has multiple backups, the sites vote to select the valid primary. If the replication service has only one backup site, a third party witness [23] can cast the deciding vote in failure diagnosis. In a real time control system, the actuator devices could implicitly serve as this witness; if a new server starts issuing commands to the actuators, the devices could ignore subsequent instructions from the previous primary site. The replication ....

J.-F. Paris, "Using volatile witnesses to extend the applicability of available copy protocols," in Proc. Workshop on the Management of Replicated Data, pp. 30-- 33, November 1992.

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