How do I make my Amazon OpenSearch Service domain more fault tolerant?

Last updated: 2021-07-30

Note: Amazon OpenSearch Service is the successor to Amazon Elasticsearch Service. 

To improve the fault tolerance of an OpenSearch Services domain, consider the following best practices:

• Take regular index snapshots.
• Use Amazon CloudWatch metrics to monitor OpenSearch Service resources.
• Understand OpenSearch Service limits.
• Use dedicated master nodes.
• Use at least three nodes.
• Enable zone awareness.
• Don't use T2 instances in production environments.

All OpenSearch Services domains take automated snapshots. Take manual index snapshots to create point-in-time backups of the data in an OpenSearch Services domain. Store the snapshots in an Amazon Simple Storage Service (Amazon S3) bucket. You can also use manual index snapshots to migrate data between OpenSearch Services domains or to restore data to another OpenSearch Services domain.

• Use the Cluster health and Instance health tabs in the OpenSearch Services console to monitor the Amazon CloudWatch metrics for your clusters.
• Create Amazon CloudWatch alarms for important OpenSearch Service metrics. For example, monitor the AutomatedSnapshotFailure metric to confirm that automated snapshots are happening at regular intervals. For a tutorial, see Get started with Amazon OpenSearch Service: Set CloudWatch alarms on key metrics.

Dedicated master nodes help prevent problems that are caused by overloaded nodes. Use dedicated master nodes when:

• Your domain is used in production environments.
• Your domain has five or more nodes.
• Your index mapping is complex, with many fields defined across types and indices.

To avoid an unintentionally partitioned network (split brain), use at least three nodes. To avoid potential data loss, be sure that you have at least one replica for each index. (By default, each index has one replica.)

Zone awareness helps prevent downtime and data loss. When zone awareness is enabled, OpenSearch Service allocates the nodes and replica index shards across two or three Availability Zones in the same Region.

Note: For a setup of three Availability Zones, use two replicas of your index. If there is a single zone failure, the two replicas ensure 100% data redundancy.

For production environments, use M-class or larger Amazon Elastic Compute Cloud (Amazon EC2) instances. If you decide to use T2 instance types, be sure to monitor the CPU credits, CPU usage, memory usage, and stability of your instances. Scale up or out when necessary.

Additionally, note the following limitations for T2 instances:

• T2 instances are assigned CPU credits. If there is a spike in network traffic, your OpenSearch Services cluster could exceed the amount of CPU credits available in your T2 instance. For more information, see CPU credits and baseline utilization for burstable performance instances.
• T2 instances have an EBS volume limit of 35 GB.
• T2 instances have a payload limit of 10 MB. Make sure that your request payload does not exceed the payload limit. For more information about OpenSearch Service network limits, see Network limits.
• T2 instance types can be used only if your OpenSearch Service instance count is ten or fewer. For more information about the supported OpenSearch Service instance types, see Supported instance types.
• T2 instance types must not be used as data nodes or dedicated master nodes. T2 instance types can become unstable under sustained heavy load. For more information, see Amazon OpenSearch Service best practices.