Quorum in synchronous replication

A quorum of data centers is used to ensure that synchronous replication is achieved even when replication is not completed across all data centers. A quorum is a majority of the number of data centers in a setup. The quorum is automatically set when you install or upgrade your setup.

The quorum is calculated by halving the number of data centers plus 1.

quorum = (number of data centers)/2 + 1

Example

If your setup has 5 data centers, your quorum would be 3.