Almost consensus: ABD and the edges of quorum replication
Summary
The article explains ABD (Attiya, Bar-Noy, and Dolev) and the edges of quorum replication, illustrating how ABD differs from full consensus and how quorum-based reads/writes work. It discusses non-atomicity, the read-back phase in ABD for linearizability, and contrasts ABD with CAS, with references to real-world systems like Cassandra.