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Conversion Procedures › Convert the Virtual Volume Size to 2000 MB

Convert the Virtual Volume Size to 2000 MB

CA Vtape supports Virtual Volumes that are 400 MB, 800 MB, or 2000 MB in size. When using CacheManagement=DYNAMIC, 2000 MB Virtual Volumes should be defined to minimize the number of multivolume tape data sets created. Defining 2000 MB Virtual Volumes does not increase DASD space usage because unused DASD space is immediately released when a Virtual Volume is dismounted.

If you have converted all of your SVTS subsystems to dynamic mode, you may want to change your Virtual Volume Size from 400 MB or 800 MB to 2000 MB.

To change your Virtual Volume Size from 400 MB or 800 MB to 2000 MB

  1. Run GRRJCL to ensure that all unexternalized Virtual Volumes are queued for externalization. Then use the SVTn Display Group and SVTn SET BACKstore commands to ensure that the Virtual Volumes are queued and being externalized.
  2. Bring down all SVTS subsystems.
  3. Execute the Define option of the CA Vtape ISPF Customization Process to generate a new SUTPARMS member with a Virtual Volume Size of 2000 MB.

    Note: Do not run any of the generated jobs.

    Run the DEFVCAT job from HLQ.CCUUJCL(DEFVCAT). This will create and initialize a new Local VCAT. You will need to run this job for each SVTS subsystem, making sure that the SVTPARMS DD statement in the job points to the SVTJCL library used for Step 3.

  4. Recover the Global VCAT from the BSDS1 by running SVTSUTIL with the following command: 
    RECOVER=GLOBAL,PREFIX=prefix,DROP_INELIGIBLE

    Note: Make sure that the SVTPARMS DD statement in this job points to the SVTJCL library used for Step 3.

  5. Restart your SVTS subsystems. They should now be able to create 2000 MB Virtual Volumes.
  6. Copy the SUTPARMS member from the SVTJCL library to the parmlib.

    Note: If you are running in dynamic mode and you convert your Virtual Volume size to 2000 MB, you can only revert back to a static mode subsystem that supports 2000 MB Virtual Volumes. 2000 MB Virtual volumes cannot be mounted by 400 MB or 800 MB SVTS subsystems.

After the Global VCAT recovery, the number of scratch tapes may increase. This occurs because the recovery will evaluate the status of each Virtual Volume recovered and rebuild the scratch pool with all Virtual Volumes that are in scratch status. The Virtual Volumes which were scratched by the last Scratch Synchronization Job run, but would not be returned to the scratch pool until the next Scratch Synchronization Job run, are being returned early to the pool by the recovery.

Since the Global VCAT recovery was run without the SCRATCH command, the Global VCAT did not scratch additional Virtual Volumes. If the SCRATCH command was accidentally included in the recovery commands, any Virtual Volume scratched by the recovery would be documented with a message in the recovery job output.