Why consider multiple subsystems

As the number of users on the system increases, a single subsystem for a set of work is often insufficient. By dividing your users into multiple subsystems you gain several advantages.

Improved manageability of work

You get better control over what work is running in each subsystem. For example, for server jobs, you might want to isolate all of the database server jobs to one subsystem, the remote command server jobs to a different subsystem, the DDM server jobs to yet a different subsystem and so on. Additionally, by using multiple subsystems you can isolate groups of jobs with their own memory pools. In this way, one group does not adversely impact other jobs.

Reduced downtime impact for users

For example, if every Friday afternoon you must bring the system to the restricted state for backup purposes, you can gradually take users offline by ending one subsystem at a time.

Improved scalability and availability

By having a single subsystem do work for fewer users, the subsystem is less busy and can be more responsive to the work requests it handles.

Improved error tolerance in interactive subsystems

By spreading the work across multiple subsystems, should a network failure occur, multiple subsystems can manage the device recovery processing.

Improved interactive subsystem startup time

You can keep the subsystem startup times shorter by subdividing the work across multiple subsystems.

Additional options for performance tuning

By using multiple subsystems you can set up the subsystems with a small number of routing entries.