High availability of a Managed Service for OpenSearch cluster

High availability of a Managed Service for OpenSearch cluster depends on the number of DATA and MANAGER hosts.

Cluster host configurationCluster host configuration

A Managed Service for OpenSearch cluster consists of one or more host groups where each host assumes a specific role.

Each OpenSearch host group can include hosts with the DATA or MANAGER roles. If a cluster has a single OpenSearch group, its hosts will have both roles.

For a cluster to be highly available and covered by a service level agreement (SLA), it must include:

1. Two or more hosts with the DATA role.
2. Three or more hosts with the MANAGER role.

Storage settingsStorage settings

When the storage is 95% full, cluster hosts automatically enter read-only mode. In this mode, data write requests fail. To prevent situations where the disk runs out of free space and the cluster becomes unavailable for writes:

• Set up alerts in Yandex Monitoring to monitor storage utilization.
• Configure automatic storage expansion.

Learn more about managing disk space in Managed Service for OpenSearch.

Maintenance settingsMaintenance settings

In multi-host clusters, hosts undergo maintenance one by one. Any host that requires a restart during maintenance will be unavailable until maintenance is complete.

Learn more about maintenance in Managed Service for OpenSearch.

Other parameters and limitationsOther parameters and limitations

Cluster availability may also be affected by:

• Backup settings.

• Storage disk type.

• Host class.

• Quotas and limits.

• Security group settings.