Cluster Deployment and Upgrade

A DolphinDB cluster consists of 4 types of nodes: controller, agent, data node, and compute node.

• Controller: The controllers are the core of a DolphinDB cluster. They collect heartbeats from agents and data nodes, monitor the node status, and manage metadata and transactions of the distributed file system. A single-machine or multi-machine cluster has only one controller. For a high-availability cluster with multiple controllers forming a Raft group, DolphinDB uses the Raft protocol to ensure strong consistency of metadata across controllers,

• Agent: An agent executes the commands issued by a controller to start/stop local data nodes. Each physical server can have only one agent configured.

• Data node: Data nodes store data and execute queries (or more complex computations). Each physical server can have multiple data nodes configured.

• Compute node: Compute nodes handle queries and computations. They respond to client requests and return results. Compute nodes work with data nodes to effectively isolate storage and computing resources. Each physical server can have zero or multiple compute nodes configured.