feat: opensearch dedicated node roles

docs/products/opensearch/concepts/dedicated-node-roles.md

@@ -0,0 +1,179 @@
+---
+title: Dedicated node roles in Aiven for OpenSearch®
+sidebar_label: Dedicated node roles
+limited: true
+---
+
+import RelatedPages from "@site/src/components/RelatedPages";
+import LimitedBadge from "@site/src/components/Badges/LimitedBadge";
+
+Aiven for OpenSearch® supports clusters with dedicated node roles, allowing you to assign specialized functions to different node groups for improved performance and scalability.
+
+The dedicated node roles feature is in
+[limited availability](/docs/platform/concepts/service-and-feature-releases#limited-availability-)
+for Aiven for OpenSearch® version 2 and later. It's available in specific service plans
+for production workloads that require enhanced performance and reliability.
+
+:::tip
+Contact Aiven to request access, learn which service plans include
+dedicated node roles, and get recommendations for your workload.
+:::
+
+## Benefits and use cases
+
+The dedicated node roles feature helps achieve the following:
+
+**Improved stability**: Separating cluster management from data operations prevents resource-intensive queries from affecting cluster coordination, reducing the risk of cluster instability.
+
+**Better scalability**: You can scale data nodes independently from cluster manager nodes, adding capacity where needed without over-provisioning management resources.
+
+**Optimized resource allocation**: Each node group can use hardware configurations tailored to its specific workload, improving cost efficiency.
+
+**Enhanced performance**: Dedicated data nodes can focus entirely on query execution and data processing without the overhead of cluster management tasks.
+
+The dedicated node roles feature is particularly beneficial for:
+
+**Large-scale deployments**: Clusters with high data volumes or query throughput benefit from isolating coordination overhead from data operations.
+
+**Performance-critical applications**: Preventing resource contention between cluster management and query execution ensures consistent performance.
+
+**Complex cluster topologies**: Larger clusters with many nodes see stability improvements when cluster management runs on dedicated hardware.
+
+## About dedicated node roles
+
+By default, OpenSearch nodes perform all roles: cluster management, data storage, and query processing. With dedicated node roles, you can separate these responsibilities across different node groups, each optimized for specific tasks.
+
+This architecture separates the cluster's control plane from its data plane, ensuring that cluster management operations remain stable even during heavy query loads or data ingestion.
+
+```mermaid
+graph TB
+    subgraph "Client apps"
+        C1[Client 1]
+    end
+
+    subgraph "OpenSearch cluster"
+        subgraph "Manager nodes"
+            CM1[Manager 1]
+            CM2[Manager 2]
+            CM3[Manager 3]
+        end
+
+        subgraph "Data nodes"
+            DN1[Data node 1<br/>Search and index]
+            DN2[Data node 2<br/>Search and index]
+        end
+    end
+
+    C1 -.->|Client requests via<br/>internal DNS| DN1
+    C1 -.->|Client requests via<br/>internal DNS| DN2
+
+    CM1 <-->|Cluster state<br/>coordination| CM2
+    CM2 <-->|Cluster state<br/>coordination| CM3
+    CM3 <-->|Cluster state<br/>coordination| CM1
+
+    CM1 -.->|Manage shards<br/>and health| DN1
+    CM1 -.->|Manage shards<br/>and health| DN2
+
+    DN1 <-->|Replicate data| DN2
+
+    style C1 fill:#e3e9ff
+    style CM1 fill:#cfeefc
+    style CM2 fill:#cfeefc
+    style CM3 fill:#cfeefc
+    style DN1 fill:#fff3e8
+    style DN2 fill:#fff3e8
+```
+
+### Available node roles
+
+#### Cluster manager nodes
+
+Cluster manager nodes handle cluster-wide operations such as:
+
+- Managing cluster state and metadata
+- Coordinating node membership
+- Creating and deleting indices
+- Tracking cluster health
+- Allocating shards to nodes
+- Orchestrating cluster-wide operations
+
+These nodes run on smaller instances optimized for low-latency coordination tasks rather than data storage. Cluster manager nodes do not store data or handle search requests, allowing them to focus on maintaining cluster stability.
+
+:::note
+Cluster manager nodes are always configured in odd numbers (typically 3) to ensure proper quorum for cluster decisions and prevent split-brain scenarios.
+:::
+
+#### Data nodes
+
+Data nodes are responsible for:
+
+- Storing and indexing data
+- Executing search queries
+- Performing data aggregations
+- Running ingest pipelines
+- Handling client requests
+- Coordinating distributed requests across the cluster
+- Providing internal DNS routing for cluster traffic
+
+In dedicated-role plans, each data node includes the data, ingest, coordinator, and internal DNS roles. Data nodes typically run on larger instances with more storage and compute resources for data-intensive operations.
+
+### Cluster configuration
+
+Dedicated node roles are defined at the service plan level. When you select a plan with dedicated roles:
+
+- Cluster manager nodes are configured as a separate node group with their own instance type
+- Data nodes form another group optimized for storage and compute
+- The configuration is managed automatically by Aiven
+- Cluster manager nodes are excluded from DNS routing for client connections
+- Node roles are assigned during cluster creation and maintained throughout the cluster lifecycle
+- OpenSearch Dashboards is served on every node
+- Dedicated dashboard nodes are not included
+
+All standard service operations work with dedicated node roles, including service creation, major version upgrades, plan changes, service forking, and node replacement. The platform handles cluster manager node operations carefully to maintain cluster stability during updates.
+
+### Node replacement and scaling
+
+During maintenance or scaling operations:
+
+- To increase data capacity, move to a dedicated-role plan with more or larger data nodes
+  while keeping the cluster manager layout unchanged.
+- Cluster manager nodes are replaced last during maintenance updates, including version
+  upgrades, to maintain cluster coordination.
+- Node failures are handled automatically with role-aware replacement.
+- Disk space validation and additional disk capacity apply only to data nodes, as cluster
+  manager nodes do not store data. This makes adding disk space more cost-efficient
+  compared to scaling disk across all nodes.
+
+## Manage dedicated node roles
+
+The dedicated node roles feature is plan-based.
+
+### Prerequisites
+
+- This is a <LimitedBadge/> feature. Contact Aiven to enable it.
+- [Upgrade Aiven for OpenSearch®](/docs/products/opensearch/howto/os-version-upgrade) to
+  2.19 or later if your service runs an older version.
+
+### Start using dedicated node roles
+
+Create an Aiven for OpenSearch® service and choose a plan that includes
+dedicated node roles. For steps, see
+[Get started with Aiven for OpenSearch®](/docs/products/opensearch/get-started#create-an-aiven-for-opensearch-service).
+
+### Configure dedicated node roles
+
+To move to another dedicated-role layout, change the service plan to a
+different eligible plan. For steps, see
+[Change a service plan](/docs/platform/howto/scale-services).
+
+### Disable dedicated node roles
+
+Change the service plan to a plan without dedicated node roles. This
+returns the service to a standard node layout where nodes share roles.
+For steps, see [Change a service plan](/docs/platform/howto/scale-services).
+
+<RelatedPages/>
+
+- [High availability in Aiven for OpenSearch®](/docs/products/opensearch/concepts/high-availability-for-opensearch)
+- [Shards and replicas](/docs/products/opensearch/concepts/shards-number)
+- [Service plans](/docs/platform/concepts/service-pricing)

sidebars.ts

@@ -1580,6 +1580,7 @@ const sidebars: SidebarsConfig = {
 
                 'products/opensearch/concepts/aggregations',
                 'products/opensearch/concepts/high-availability-for-opensearch',
+                'products/opensearch/concepts/dedicated-node-roles',
                 'products/opensearch/concepts/opensearch-vs-elasticsearch',
                 'products/opensearch/concepts/shards-number',
                 'products/opensearch/concepts/cross-cluster-replication-opensearch',