Causal Consistency for Geo-Replicated Cloud Storage under Partial Replication

Data replication is a common technique used for fault-tolerance in reliable distributed systems. In geo-replicated systems and the cloud, it additionally provides low latency. Recently, causal consistency in such systems has received much attention. However, all existing works assume the data is fully replicated. This greatly simplifies the design of the algorithms to implement causal consistency. In this paper, we propose that it can be advantageous to have partial replication of data, and we propose two algorithms for achieving causal consistency in such systems where the data is only partially replicated. This is the first work that explores causal consistency for partially replicated geo-replicated systems. We also give a special case algorithm for causal consistency in the full-replication case.