Workload Manager helps you control the allocation of system resources by defining classes of service and allocating resources to each of these classes.

Each class has a set of attributes that determine what its resource entitlements are, as well as other behaviors. Every process on the system is classified into a service class, and is thus subject to enforcement of the resource entitlements and behaviors for that class. Processes are assigned to a class either manually using manual assignment, or automatically according to user-defined classification rules.

WLM supports two levels of classes: superclasses and subclasses. Super classes are given resource entitlements based on available system resources, and subclasses are given resource entitlements relative to the entitlements of their associated superclass. Optionally, you can define subclasses to allow for more granular control of the processes in a superclass. You can also delegate the responsibility of defining subclasses by specifying an admin user or admin group for a superclass.

For both the superclass and subclass levels, you can define classes, resource shares and limits, and rules using SMIT, or the command-line interface. Applications can use the WLM APIs. Configuration definitions are kept in a set of text files called the WLM property files.

A class name is up to 16 characters in length and can contain only uppercase and lowercase letters, numbers and underscores (_). For a given WLM configuration, each superclass name must be unique. Each subclass name must be unique within that super classes, but it can match subclass names in other super classes. To uniquely identify every subclass, the full name of a subclass is composed of the superclass name and the subclass name separated by a dot; for example: Super.Sub.