# AOSPERF05-BP01 Enable a dedicated leader node for OpenSearch Service domain
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 Configure dedicated leader nodes with appropriate instance types to improve cluster stability and performance. This separation of cluster management tasks helps prevent split-brain scenarios and optimizes resource utilization as your OpenSearch Service domain grows. 

 **Level of risk exposed if this best practice is not established**: High 

 **Desired outcome**: Your OpenSearch Service domain has dedicated leader nodes with appropriately sized instances to handle cluster management tasks. This configuration improves cluster stability, prevents split-brain scenarios, and maintains performance as your workload grows. 

 **Benefits of establishing this best practice:** 
+  Improved cluster stability through isolated cluster management tasks 
+  Enhanced reliability by preventing split-brain scenarios and reducing election times 
+  Better resource utilization with workload separation from data nodes 
+  Increased scalability and performance as your domain grows 
+  Reduced risk of operational disruptions 

## Implementation guidance
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 Dedicated manager nodes' size is directly tied to instance size, number of instances, indexes, and shards they manage. For production clusters, we recommend, at a minimum, the following instance types for dedicated managing nodes. 


|  Instance count  |  Manager node RAM Size  |  Maximum supported shard count  |  Recommended minimum dedicated manager instance type  | 
| --- | --- | --- | --- | 
|  1–10  |  8 GiB  |  10K  |  m5.large.search or m6g.large.search  | 
|  11–30  |  16 GiB  |  30K  |  c5.2xlarge.search or c6g.2xlarge.search  | 
|  31–75  |  32 GiB  |  40K  |  r5.xlarge.search or r6g.xlarge.search  | 
|  76–125  |  64 GiB  |  75K  |  r5.2xlarge.search or r6g.2xlarge.search  | 
|  126–200  |  128 GiB  |  75K  |  r5.4xlarge.search or r6g.4xlarge.search  | 

### Implementation steps
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+  Log in to the [AWS Management Console](https://console.aws.amazon.com). 
+  Navigate to the Amazon OpenSearch Service console. 
+  Create a new domain or modify an existing domain: 
  +  For a new domain, choose **Create domain**. For an existing domain, select the domain name and choose **Actions**, then **Edit cluster configuration**. 
+  Enable dedicated leader nodes: 
  +  In the Cluster configuration section, under Dedicated master nodes, toggle on the option to enable dedicated leader nodes. 
+  Choose leader node instance type and count: 
  +  **Instance type:** Select an instance type that fits the workload needs. For detailed information on choosing the right instance type for leader roles, see [AOSPERF05-BP02](aosperf05-bp02.md). 
  +  **Instance count:** Select three or five. Three is usually more than enough for the majority of workloads. 
+  After configuring the settings, review your setup and choose **Create** (for a new domain) or **Save changes** (for an existing domain). 

## Resources
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+  For information about how certain configuration changes can affect dedicated leader nodes, see [Making configuration changes in Amazon OpenSearch Service.](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/managedomains-configuration-changes.html) 
+  [Learn how to add dedicated manager nodes in your OpenSearch Service domain](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/managedomains-dedicatedmasternodes.html) 
+  For clarification on instance count limits, see [OpenSearch Service domain and instance quotas](https://docs.aws.amazon.com/general/latest/gr/opensearch-service.html#opensearch-limits-domain). 
+  For more information about specific instance types, including vCPU, memory, and pricing, see [Amazon OpenSearch Service prices](https://aws.amazon.com/opensearch-service/pricing/).