Synchronous replication requires an operational ArangoDB cluster.

Enabling synchronous replication

Synchronous replication can be enabled per collection. When creating a collection you may specify the number of replicas using the replicationFactor parameter. The default value is set to 1 which effectively disables synchronous replication.

Example:> db._create("test", {"replicationFactor": 3})

In the above case, any write operation will require 2 replicas to report success from now on.

Preparing growth

You may create a collection with higher replication factor than available. When additional db servers become available the shards are automatically replicated to the newly available machines.

Multiple replicas of the same shard can never coexist on the same db server instance.