Define and Maintain the Workload Best Practices › Use VRM

Use VRM

Use Virtual Resource Management (VRM) to control sequencing and submission of the workload.

The essential function of CA WA CA 7 Edition is to schedule work and track its progress. A job is considered scheduled by CA WA CA 7 Edition when it enters the request queue. But once work is scheduled, it must be sequenced properly. Jobs have to run in the correct order and not run until all necessary resources are available. CA WA CA 7 Edition determines resource availability in various ways. A resource can be made ready on the completion of a job or when a data set is created. A user command such as VERIFY or POST can also signal the availability of a resource.

The LOAD process discussed earlier in this document defines data set dependencies automatically. Job requirements can be added so that job sequencing is ensured. However, sometimes jobs have to wait on resources other than jobs or data sets. VRM lets you wait. To use VRM, you create a resource profile for the job (RM.1). This profile names the resources that are needed, describes how they are used to control sequencing and when they are no longer needed.

Virtual resources are not evaluated until all the standard resource requirements of the job are met.

Business Value:

Using VRM to control job submission helps ensure that CPU resources are balanced.

Additional Considerations:

The type of virtual resource influences how the job is sequenced. A resource that is defined as shared (SHR) can have any number of concurrent users. Thus, any number of jobs can run in parallel using a shared resource. But if a profile for a job specifies exclusive (EXC) use of a resource, no other job referring to that resource can run while that job runs.

• The resource count (RCT) type is like an SHR resource except that it has a numeric limit on the number of concurrent uses. In the resource profile of the job, you indicate the number of units of the resource that are used. Specify this number as part of the resource name. Then on a different panel (RM.7), declare the global limit of concurrent uses.
• A co-requisite (CRQ) resource is either active (present) or inactive (absent). You activate and deactivate a CRQ resource manually using the PRSQA and PRSQD commands. When you refer to a CRQ resource in a resource profile, you indicate whether the resource must be active (FREE=A) or inactive (FREE=I) to run.
• The address space resource (ASX) is also either active or inactive. The status of these ASX resources is determined through scans of ASCB chains maintained by z/OS on the CA7ONL host computer. When you refer to an ASX resource in a resource profile, you indicate whether the address space must be active (FREE=A) or inactive (FREE=I) to run.

Virtual resource conditions are evaluated while the job is in the ready queue. When all the resource conditions specified in the profile are satisfied, the job is eligible for submission. But if one or more conditions cannot be satisfied, the job waits in the ready queue with a status of W-RSRC. The job remains in this state until all resource conditions are satisfied.

Resource conditions can be satisfied automatically (for example, a job using a resource completes) or in response to a manual command: PRSCF, PRSQA, or PRSQD.

When you define an SHR, EXC or RCT resource, you also indicate when it is to disassociate the resource and job dynamically. The FREE value indicates this time. (This value is also used when defining CRQ and ASX resources, but there the meaning is different. When defining a CRQ or ASX resource, the FREE value indicates the state of the resource that is needed for the job to run.)

The most common disposition is FREE=Y. This disposition means to free the resource only in case of normal termination. If FREE=Y is specified and the job abends, the resource remains associated with the job until the job terminates successfully or is manually freed.

You can indicate that a job frees the resource only in the case of abnormal termination (FREE=A).

A profile can indicate always to free the resource when the job finishes without regard for the completion status of the job(FREE=F).

You can also indicate never to free a resource automatically (FREE=N). Free these resources with a command (PRSCF).