Understanding expiration processing and scratch tapes

The expiration process runs once daily based on the time specified in the EXPSTART configuration statement. The expiration process will:

  • Select any volume that has a use status of Used and an expiration date less than the date on which the process runs.
  • Change the use status to Free and the expiration date to zeros for any of the selected volumes that are not bypassed for one of the following reasons:
    • A system hold is in effect (System Hold Flag indicates Hold).
    • A user hold is in effect (User Hold Flag indicates Hold).
    • A volume is an external volume (Internal/External Flag indicates External).
  • Write an explanatory message to the TxTMM console when a volume selected for expiration processing is bypassed.
  • For volumes that are not bypassed, move any volume that resides in a pool, with an associated free pool, back to the free pool, unless there is a DSE operation pending for a volume.

Scratch mount requests

A volume that has a use status of Free will always have an expiration date of zeros. However, a status of Free is not sufficient for the volume to qualify as a scratch volume. The following requirements must be met for a volume to be eligible to satisfy a scratch mount request:

  1. The use status of the volume is Free (Use Status Flag indicates Free).
  2. There is not a "user hold" on the volume (User Hold Flag indicates No Hold).
  3. There is not a "system hold" on the volume (System Hold Flag indicates No Hold).
  4. The volume is an internal volume (Internal/External Flag indicates Internal).
  5. The volume does not have a DSE action pending (DSE Flag indicates No DSE).
  6. The volume is not enqueued by another Tape Manager request.
  7. If the volume is in an automated tape library then the library status must be ONLINE.

The first five items in this list are related to volume attributes and hold conditions that can be reported by the TAPEQRY command. Volume attributes and hold conditions are described in the next section.

The last two items are runtime conditions. Volumes that are enqueued can be determined with the TAPEREQ ENQ command. The status of an automated tape library can be determined using the TAPELIB QRY command.

As an example, the following command can be used to determine all of the volumes in the system free pool that are eligible to satisfy a scratch mount request (runtime conditions permitting):

tapcmd tapeqry pool sys only status f hstat n sstat n int nodse
Note: If you take volumes offsite, consider placing a user hold on those volumes. By doing this, if a volume reaches its expiration date while offsite, the hold status will prevent Tape Manager from expiring it and therefore prevent Tape Manager from attempting to use the volume to satisfy a scratch request.