Zones and regions

Keep some customers' data on the machines of one region with zones.

Keep some customers' data only on the machines of one region, for example to meet a data residency rule. Zones restrict the replicas of some shard key intervals to some nodes.

Requirements

A collection with a shard key that carries the region, such as { region: 1, _id: 1 }.
A user with the privileges of the sharding commands.

Assign the nodes to the zone

Each node is a shard whose name is the one listShards shows. Assign the nodes of that region to the eu zone:

JavaScript

sh.addShardToZone("<shard>", "eu");

Assign the interval to the zone

JavaScript

sh.updateZoneKeyRange("shop.orders", { region: "eu", _id: MinKey }, { region: "eu", _id: MaxKey }, "eu");

Check

teseladb admin ranges --collection shop.orders shows that the eu ranges only have replicas on the nodes of the zone.

Common problems

With every replica of a range in one region, each write waits for a majority of that region. With replicas in distant regions, the write waits for the network between them.