Which component is responsible for maintaining state information of all notebooks attached to the cluster?

The driver node is the component that maintains the state information of all notebooks attached to the cluster. In a Databricks environment, the driver node is responsible for executing the main function of the application and managing the overall execution. It handles tasks such as scheduling, monitoring, and coordinating the work of the Spark executors.

By keeping track of the state information, including the status of running commands and the variables defined in the notebooks, the driver node ensures that all user interactions and computations are managed cohesively. This is crucial in a collaborative setting where multiple notebooks may be running simultaneously, as it allows for effective resource management and communication within the cluster.

Other components like worker nodes and Spark executors handle the processing of tasks assigned by the driver but do not maintain the state specific to the notebooks. The master node is responsible for the overall management of the cluster but does not participate in the execution or the state management of individual user notebooks, which is why those options do not align with the responsibility of maintaining state information.