node_capacity_type

Description

The node_capacity_type parameter specifies the type of capacity for the cluster nodes. It can be set to on_demand, spot, or mixed.

  • on_demand: Uses AWS on-demand instances for the cluster nodes.
  • spot: Uses AWS spot instances for the cluster nodes.
  • mixed: Creates one node group with on-demand instances and the other two with spot instances. Use mixed with the min_on_demand_count and max_on_demand_count parameters to control the minimum and maximum number of on-demand nodes, ensuring acceptable service availability even if spot instances become unavailable.

Default Value

The default value for node_capacity_type is on_demand.

Use Cases

  • Cost Optimization: Use spot or mixed capacity types to reduce costs by leveraging lower-cost spot instances while maintaining a baseline of reliable on-demand instances.
  • Reliability and Performance: Use on_demand capacity type for maximum reliability and performance, as on-demand instances are not subject to interruption like spot instances.

Setting Parameters

To set the node_capacity_type parameter, use the following command:

$ convox rack params set node_capacity_type=mixed -r rackName
Setting parameters... OK

This command sets the node capacity type to mixed.

Additional Information

When using the mixed capacity type, it is important to configure the min_on_demand_count and max_on_demand_count parameters to ensure that your cluster maintains the desired balance of cost and reliability.

Using spot instances can lead to potential volatility as these instances may be interrupted by AWS when capacity is needed elsewhere. This setup is recommended only for non-production environments that can tolerate such interruptions.

By setting the node_capacity_type parameter appropriately, you can optimize the cost-efficiency and reliability of your Convox rack based on your specific needs and workload requirements.