An Arbitrary 2D Structured Replica Control Protocol

Traditional replication protocols that logically arrange the replicas into a specific structure have reasonable availability, lower communication cost as well as system load than those that do not require any logical organisation of replicas. We propose in this paper the A2DS protocol: a single protocol that, unlike the existing proposed protocols, can be adapted to any 2D structure. Its read operation is carried out on any replica of every level of the structure whereas write operations are performed on all replicas of a single level of the structure. We present several basic 2D structures and introduce the new idea of obtaining other 2D structures by the composition of several basic ones. Two structures are proposed that have near optimal performance in terms of the communication cost, availability and system load of their read and write operations. Also, we introduce a new protocol that provides better performance for its write operations than those of ROWA protocol while preserving similar read performance. 1998 ACM Subject Classification Fault tolerance, Distributed systems.