Brief Announcement: CausalEC: A Causally Consistent Data Storage Algorithm based on Cross-Object Erasure Coding

Current causally consistent data storage algorithms use partial or full replication to ensure data access to clients over a distributed setting. We develop, for the first time, an erasure coding based algorithm called CausalEC that ensures causal consistency for a collection of read-write objects stored in a distributed set of nodes over an asynchronous message passing system. CausalEC can use an arbitrary linear erasure code for data storage, and ensures liveness, fault-tolerance and storage properties prescribed by the erasure code. Unlike previous consistent erasure coding based algorithms, CausalEC is compatible with cross-object erasure coding, where nodes encode values across multiple objects. Every write operation in CausalEC is "local", that is, a server performs only local actions before returning to a client that issued a write operation. A read operation to an object can be returned by a server on contacting a small subset of other servers so long as the underlying erasure code allows for the object to be decoded from that subset.