Server Grid Option in Informatica 7.X

A server grid is a server object that distributes sessions in a workflow to servers based on server availability. Grid is used to o balance the server workload which increases workflow performance.

Multiple PowerCenter Servers can be added to grid. Grid maintains the connectivity between all servers connected in grid.

A server grid contains information about other servers in the grid. PowerCenter Server fetches the server grid object and creates a TCP/IP connection to the other servers in the grid.

Each server in the grid monitors the other servers to check connectivity status. As a result, the grid notifies each server when add, edit, or delete of any server in the grid.

If a PowerCenter Server loses its connection to the grid, it tries to reestablish a connection. When a PowerCenter Server cannot reestablish a connection to the grid, session and workflow completion depends on factors such as shut down mode and which server loses connectivity.

These servers can be classified into two categories based on the tasks they perform.

1. Master Server: The PowerCenter server to which workflow is assigned and run, is called as Master Server. Master server starts the workflow, runs all non-session tasks and assigns sessions to run on other servers in grid.
The master server distributes sessions that are ready to run to available worker servers in a round-robin fashion based on server availability.

2. Worker Server: A worker server is a server that runs sessions assigned to it by a master server.
If a worker server is running the maximum number of concurrent sessions, the master server assigns another worker server to run the session. If all worker servers are running the maximum number of concurrent sessions, the master server places the session in its own ready queue.

By default, each PowerCenter Server in a server grid is both a master server and a worker server. This means that a server in a grid can distribute sessions to and receive sessions from every server in the grid.

The server grid distribution options can be set at the server level, workflow level, and session level. PowerCenter Servers specified at the session level override both server level and workflow level properties.

In below diagram, Master Server C distributes tasks/sessions to all other worker server (A & B), at the same time, if there is any non-session task, which will be executed on Master Server Only.

In Informatica 7.X, a single session can be assigned to only one Worker server to execute it. There is no provision to run a single session on multiple worker servers to improve performance.