When you run a workflow on a grid, the PowerCenter Integration Service designates one service process as the master service process, and the service processes on other nodes as worker service processes. The master service process can run on any node in the grid.

The master service process receives requests, runs the workflow and workflow tasks including the Scheduler, and communicates with worker service processes on other nodes. Because it runs on the master service process node, the Scheduler uses the date and time for the master service process node to start scheduled workflows. The master service process also runs the Load Balancer, which dispatches tasks to nodes in the grid.

Worker service processes running on other nodes act as Load Balancer agents. The worker service process runs predefined Event-Wait tasks within its process. It starts a process to run Command tasks and a DTM process to run Session tasks.

The master service process can also act as a worker service process. So the Load Balancer can distribute Session, Command, and predefined Event-Wait tasks to the node that runs the master service process or to other nodes.

For example, you have a workflow that contains two Session tasks, a Command task, and a predefined Event-Wait task.

The following figure shows an example of service process distribution when you run the workflow on a grid with three nodes:

When you run the workflow on a grid, the PowerCenter Integration Service process distributes the tasks in the following way: