Backend & systems·Consistency and replication
you require three of the five nodes to acknowledge a write and two to answer a read, so the two sets always overlap.
Quorum
Also calledR + W > N, majority quorum
Requiring acknowledgement from a subset of replicas such that read and write sets are guaranteed to intersect. It gives tunable consistency: raise W for durability, raise R for freshness, keep R + W greater than N for overlap. Quorum reads still return stale data under some failure interleavings, so it is not the same as linearisability.