JSS hold extensions

This section introduces you to the job hold extensions available with the Job Setup Services, a feature of ThruPut Manager.

Introduction

JSS needs to be able to determine whether or not a job is being held because its setup requirements have not yet been met. Since the standard JES2 hold function is inadequate for this task, ThruPut Manager extends the JES2 system hold.

Since ThruPut Manager extends the JES2 hold facility, any standard JES2 hold is completely unaffected. Jobs that have been held by some action not connected with JSS will not be released when JSS holds are removed.

Automated Hold/Release

Through the architecture of the Control File Manager and the Control File, ThruPut Manager adds several new types of hold to the single JES2 system hold. Two holds are provided by Job Setup Services: the HSM Time Delay Hold and the VVS hold.

HSM Hold

JSS provides an early data set recall for DFHSM migrated data sets. Whenever you request early data set recall, it is possible to place a time delay on the job to give the system the opportunity to complete the recall. The job is placed in HSM hold until the delay time expires.

The recall mechanism allows you to differentiate between data sets migrated to DASD and data sets migrated to tape.

Note that the delay is a "timer" mechanism independent of the actual data set recall process.

VVS HOLD

Virtual Volume Staging provides a facility to pre-stage Virtual Volumes that are needed by jobs that have been processed by the analyzer. It supports the Virtual Tape technologies from the following vendors:

  • IBM
  • StorageTek
  • CA-Vtape (software)

We refer to volumes as VIRTUAL volumes regardless of where they are stored. We also refer to volumes that are in cache as ONLINE Virtual Volumes. Virtual Volumes that are on physical tape are referred to as OFFLINE Virtual Volumes.

During the analysis process, using the interfaces provided by the vendors, ThruPut Manager detects the location of Virtual Volumes. For a given job a list of OFFLINE volumes is constructed.

Facilities are provided in JAL to request the pre-staging of OFFLINE Virtual Volumes. Jobs that request pre-staging are held automatically. They are released when all the volumes that were offline have been staged.

The pre-staging JAL directive requires a MAX_HOLD time to be specified. The job is released when all volumes have been staged, or the maximum time has expired, whichever comes first.

Virtual Volume Staging occurs on the system which analyzed the job.

StorageTek Approach:

ThruPut Manager makes use of StorageTek's interface to request Virtual Volume Staging. The request is initiated in the ThruPut Manager address space. Up to two requests per Virtual Library can be active at any given time.

A queue of volumes to be staged is maintained by ThruPut Manager. The queue is maintained in a FIFO order for each Virtual Library.

IBM/CA-Vtape Approach:

No API is provided to request Virtual Volume Staging. As a result, a different approach must be provided.

When a Virtual Volume Staging request is needed, ThruPut Manager uses an address space, TMVVS, to service Virtual Volume Staging requests. If the TMVVS address space exists, the request is queued to that address space. If it doesn't, ThruPut Manager creates one using the IBM IEESYSAS JCL procedure. 

Staging requests are made by using dynamic allocation. No OPEN is issued, so there are no security considerations in terms of read/write.

Two requests per Virtual Library are allowed in parallel.

TMVVS address spaces are terminated if they idle for 15 minutes or more. If needed again, they are recreated.

Note that if TMSS is shut down while staging is in progress, the staging address spaces will complete any staging that is currently in progress. Upon a restart, TMSS will recognize that staging has completed and release the job.

Canceling the TMVVS address space cancels the stage request and the job can be released if this was the last volume for the job to be staged.

Control File Considerations

JSS requires the Control File. All the information needed to manage the new types of job hold is maintained in this file. For a description of the Control File, refer to File Definition Services (FDS) Function.

Operational Considerations

JSS provides operator commands to manage the new types of holds:

  • JSS DISPLAY JOBS - Displays JSS information by job.
  • JSS DISPLAY HOLD - Displays information by JSS hold category.
  • JSS DISPLAY JOBS HOLD (VVS) - Displays jobs with VVS hold applied.
  • JSS DISPLAY VVSQ - Displays job or volumes awaiting VVS.
  • JSS RECONCILE VVS - Reconciles VVS queue with JES2 queue.
  • JSS RELEASE - Releases a JSS-managed Job.

Except for jobs in OPERATOR hold, intervention to release jobs from JSS holds should be rare. Jobs in VOLUME, HSM and VVS holds are normally released automatically.

End User Considerations-Display Facilities

The User Display Services facility has been extended to allow users to distinguish JSS holds from ordinary JES2 holds. For more information refer to User Display Facility (UDF). 


 

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