Abstract:
Multi-master update everywhere database replication, as achieved by protocols based on group communication such as DBSM and Postgres-R, addresses both performance and availability. By scaling it to wide area networks, one could save costly bandwidth and avoid large round-trips to a distant master server. Also, by ensuring that updates are safely stored at a remote site within transaction boundaries, disaster recovery is guaranteed. Unfortunately, scaling existing cluster based replication protocols is troublesome. In this technical report we present a database replication protocol based on group communication that targets interconnected clusters. In contrast with previous proposals, it uses a separate multicast group for each cluster and thus does not impose any additional requirements on group communication, easing implementation and deployment in a real setting. Nonetheless, the protocol ensures one-copy equivalence while allowing all sites to execute update transactions. Experimental evaluation using the workload of the industry standard TPC-C benchmark confirms the advantages of the approach. This technical report is a reworked version of a paper submitted to PRDC 2006. But in that version, we present a general algorithm and focus the theoretical discussion on serializability. In addition, this version includes a consistency discussion arguing that our protocol do in fact provide snapshot isolation.

BibTeX Entry:

@TECHREPORT{wice-si-techrep,
  author = {J. Grov and L. Soares and A. Correia Jr. and  J. Pereira and R. Oliveira and F. Pedone},
  title = {WICE-SI: Pragmatic Inter-Cluster Replication},
  institution = {Univ. do Minho},
  year = {2006},
}