Operational best practices for Amazon OpenSearch Service

deploy mission critical domains across 3 AZ and 2 replica shards per index.

provision instances in multiples of 3 so that instances are distributed equally across ( the 3 ) AZs

use 3 dedicated master nodes ( a master node performs cluster management tasks but does not hold data and does not respond to data upload requests, thus increasing the stability of the domain/cluster).

if not possible (some regions have less AZ) have at least 2 AZ with equal number of instances and 1 replica.

create domain within a VPC and setup restrictive resource-base policies or fine grained access control.

Enable encryption in transit and at rest