Elasticsearch domains should have at least three data nodes

NIST

Description

Ensures Elasticsearch domains are configured with at least three data nodes for high availability.

To configure an Elasticsearch domain with at least three data nodes, follow these steps:

Open the Amazon Elasticsearch Service console at https://console.aws.amazon.com/es/.
Choose the domain that you want to modify.
In the navigation pane, under Domain configuration, choose Elasticsearch cluster.
Set the number of instances to 3 or more.
Choose Save changes.

NIST