-Under normal circumstances, for an account with strong consistency, a write is considered committed when all regions acknowledge that the record has been replicated to it. However, for accounts with 3 regions or more (including the write region), the system can "downshift" the quorum of regions to a global majority in cases where some regions are either unresponsive or responing slowly. At that point, unresponsive regions are taken out of the quorum set of regions in order to preserve strong consistency. They will only be added back once they are consistent with other regions and are performing as expected. The number of regions that can potentially be taken out of the quorum set will depend on the total number of regions. For example, in a 3 or 4 region account, the majority is 2, so only 1 region can be removed. For a 5 region account, the majority is 3, and 2 unresponsive regions can be removed. This capability is known as "dynamic quorum" and can improve both write availability and replication latency for accounts with 3 or more regions.
0 commit comments