Recovering in large distributed systems with replicated data

The problem of recovery in large-scale transaction-based distributed systems with replicated data is studied. In large distributed systems the cost of accessing data items may be considerably greater, because of the distances involved. It is thus important to exploit replication to reduce data-access times. Also, in large systems, failure events are much more frequent than in small systems. Therefore, executing costly recovery protocols, such as the ones needed to update stale, newly-recovered replicas or to resolve the uncertainty of recovering replicas, must be avoided. These protocols are called dependent recovery protocols, since they require a recovering site to consult other sites before it can be reintegrated into the distributed system. Independent recovery has been proved unattainable in one-copy systems. It is shown that independent recovery is possible in systems with replicated data by contributing such a protocol. Simulation and analytical studies of its performance and availability characteristics are reported.<
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