blockchain//consensus//Quorum

A quorum is the minimum number of valid signatures needed to produce a block, \(\lfloor N/2\rfloor+1\) for \(N\) validators.

A quorum is the minimum number of valid signatures needed to produce a block, ⌊N/2⌋+1\lfloor N/2\rfloor+1⌊N/2⌋+1 for NNN validators.

The formula makes small networks fragile. With 2 validators the quorum is 2, so there is no fault tolerance at all: if either goes down the network stalls, and a 2-validator network has no high availability because both must be online at all times. With 3 validators the quorum is 2 and one failure is tolerated; with 4 the quorum is 3 and still only one failure is tolerated.