Gifford's 1979 weighted-voting scheme keeps replicated files consistent by requiring read and write quorums whose votes sum to more than the total

David K. Gifford, then a Stanford graduate student working at Xerox PARC (the work supported in part by the Xerox Corporation and by the Fannie and John Hertz Foundation), generalized earlier majority-consensus replication schemes by assigning each copy of a replicated file a tunable number of votes. In his own words: "Every copy of a replicated file is assigned some number of votes. Every transaction collects a read quorum of r votes to read a file, and a write quorum of w votes to write a file, such that r+w is greater than the total number of votes assigned to the file." Because r + w exceeds the total vote count, every read quorum necessarily shares at least one copy with the most recent write quorum — so a read can always find a current version. The scheme was implemented in PARC's "Violet" system.

The design's payoff is that per-copy vote weights make reliability and performance separately tunable: a copy on fast, reliable storage can be given more votes than a copy on a flaky remote node, and the r/w split trades read latency against write latency. Simple majority consensus is the special case where every copy holds one vote and quorums are bare majorities.

This is a consistency mechanism, not a theory of political power — but it fixes the vocabulary ("weighted voting," "quorum") that later recurs, critically, in law and in financial regulation, a lineage drawn out in observation-weighted-voting-power-gap-recurs-across-cs-law-regulation. It belongs to the same distributed-consensus history as Lamport's Paxos, which reached for a parliamentary allegory to describe agreement among replicas rather than an actual voting arithmetic.