Scheduling environments help ensure that units of work are sent to systems that have the appropriate resources to handle them. A scheduling environment is a list of resource names along with their required states. Resources can represent actual physical entities, such as a data base or a peripheral device, or they can represent intangible qualities such as a certain period of time (like second shift or weekend).
These resources are listed in the scheduling environment according to whether they must be set on or off. A unit of work can be assigned to a specific system only when all of the required states are satisfied. This function is commonly referred to as resource affinity scheduling.
Figure 1 shows a simple scheduling environment example. The arriving work units, X, Y, and Z, could be batch jobs submitted through JES2 or JES3. Each of the jobs had a scheduling environment associated with it at the time it was submitted (in this case the X and Y jobs are each associated with the A scheduling environment, and the Z job is associated with the B scheduling environment).
JES checks the scheduling environment associated with each arriving batch job and then assigns the work to a system that matches that scheduling environment. In the example, both the X and Y jobs require that both Resource P and Resource Q be set to ON, so those jobs can be initiated only on System 1 in the sysplex. The Z job requires that Resource P be set to ON and that Resource Q be set to OFF. So that job can be initiated only on System 2.
In a sysplex containing only one system, scheduling environments have some degree of usefulness, as JES will hold batch jobs until the required states become satisfied. In a multisystem sysplex, the full power of scheduling environments becomes apparent, as work is assigned only to those systems that have the correct resource states (the resource affinity) to handle that work.
Presently, JES2 and JES3 are the only participants that use scheduling environments, although the concepts could certainly apply to other types of work in the future.
See Defining scheduling environments for a description of how to define scheduling environments to workload management.