Consumable resources are resources available on machines in your LoadLeveler cluster. They are called "resources" because they model quantities of commodities or services available on machines (e.g., cpus, real memory, virtual memory, software licenses, DASD, etc). They are considered "consumable" because job steps use some specified amount of these commodities when they are running. Once the step is completed, the resource becomes available for reuse by another job step.
Consumable resources which model the characteristics of a specific machine (e.g., its number of cpus, or the number of a specific software licenses available only on that machine) are called machine resources. Consumable resources which model resources that are available across the LoadLeveler cluster (such as floating software licenses) are called floating resources. For example, consider a configuration with 10 licenses for a given program (which can be used on any machine in the cluster). If these licenses are defined as floating resources, all 10 can be used on one machine, or they can be spread across as many as 10 different machines.
The LoadLeveler administrator can specify:
The user submitting jobs can specify the resources consumed by each task of a job step.
The LoadLeveler scheduling algorithms use the availability of the requested consumable resources to determine the machine or machines on which a job will run. Consumable resources are used only for scheduling purposes and are not enforced like other limits, such as wall clock limits. Once a job is scheduled, LoadLeveler does not ensure that the amount of resources used is equal to the amount requested. LoadLeveler's negotiator daemon keeps track of the amounts of consumable resources available, reducing them by amounts requested when a job step is scheduled, and increasing them when a consuming job step completes.
LoadLeveler does not attempt to obtain software licenses or to verify that software licenses have been obtained, when consumable resources are used to model software licenses. By providing a user exit to be invoked as a submit filter, the LoadLeveler administrator may provide code to obtain a software license and run the job step only after a license has been successfully obtained. For more information on filtering job scripts, see Filtering a Job Script.