Sloppy quorum
A variant of quorum where a write is accepted by any N available nodes — not necessarily the N that "own" the data — when the proper nodes are unavailable. It increases write availability under failures, at the cost of the consistency guarantee.
Problem: a strict quorum requires W of the N "home" nodes to respond; if too many are down (or partitioned away) the write fails. A sloppy quorum instead lets other, reachable nodes temporarily accept the write (with a "hint" about who it really belongs to). When the home nodes return, the substitute nodes deliver the data onward via hinted handoff. Win: the system can keep taking writes even when the right nodes are unavailable → maximum availability (the Dynamo philosophy "always writeable"). Price: the W + R > N guarantee doesn't hold strictly under failures — a read can miss a write that sits on a temporary node. A classic Dynamo/Cassandra/Riak mechanism. Related to quorum read and anti-entropy.