ScaleGrid now supports replica sets with arbiters in our fully managed MongoDB Cloud plans! This gives you a lower cost high availability option – you can keep two full copies of your data and one arbiter. Arbiters are voting members of the replica set and do not store any data.
The MongoDB create wizard also gives you the option to choose the machine pool, or Cloud Profile of the arbiter. This is especially useful for regions that have only two availability zones, for example, Singapore, Sydney, and Sao Paulo, and N. California.
The recommended topology is to deploy two full replicas in two different availability zones (in the same region), and then move the arbiter to a different region. If you choose the same region for the first two replicas, ScaleGrid will automatically distribute the servers across different availability zones. With this configuration, even if an entire availability zone goes down, two of your servers are up and your database will be up.
Learn more about geographically distributing your MongoDB clusters to achieve high availability for your deployments.