This topic discusses the role of Dremio services and how they are implemented on a deployment.
A Dremio cluster consists of:
- One or more coordinator nodes.
- One or more executor nodes.
The coordinator node has the special function of managing metadata and is enabled with the master-coordinator role.
The Dremio services property determines whether the node is enabled with the
master-coordinator or executor role.
[info] Master-Coordinator Role
All Dremio cluster nodes with Dremio coordinator services must have the master-coordinator role enabled. A node with only the coordinator role enabled is not supported.
The coordinator node is responsible for:
- Query planning
- Serving Dremio's UI
- Handling client connections
- Managing metadata
If you are implementing High Availability, you can setup more that one coordinator node. In this case, the additional nodes are used as backup should the coordinator node fail.
Executor nodes are responsible for query execution.
Single Node and Cluster Deployments
- In single node deployments, both execution and coordination happens on the same node.
- In cluster deployments, a given node may only have a single role: either a coordinator or an executor. Multiple roles per node are not supported in cluster deployments.