Understanding category managed media

The need for Tape Manager to manage categories was emphasized with the increased usage of virtual (or logical) volumes. With those systems, it can be useful to set the library category of a volume to a fast-ready (or scratch) category when a volume becomes an eligible scratch volume, which can occur because of expiration processing or by issuing commands, such as TAPEMOD or POOLDEL.

The fast-ready scratch category ensures that data associated with a volume is not recalled when Tape Manager performs a scratch mount. If the intent is to specify a fast-ready category, verify that the Scratch Category is defined in the library accordingly. Tape Manager will attempt to manage the library category code so that it is consistent with the Tape Manager scratch status, but Tape Manager does not use the category code for scratch mounts.

As of PTF UI54509, for IBM automated tape libraries, Tape Manager allows the specification of Scratch Category and Volume Category codes when a media type is defined. The change enables Tape Manager to manage the library category code of volumes of the corresponding media type when using a Tape Manager (i.e., non-RMM) catalog. When a volume becomes eligible to be used as a scratch volume, for example, during expiration processing, the category will be set to the Scratch Category. When a volume transitions from a scratch status to a non-scratch status, the category will be set to the Volume Category.

For Scratch Categories, Tape Manager supports scratch and expiration processing in IBM automated tape libraries, allowing you to more efficiently manage cache (disk) space in the library. Based on the settings you define in the library for each Scratch Category, expired tape contents are removed from the cache, allowing more space for active tape content.

Tape Manager also allows you to prevent using an expired tape as a scratch tape during the expiration period defined in the library for the Scratch Category. During Tape Manager expiration processing for a volume that has a Scratch Category (ScrCat) and Expiration Hold period (ExpHold) defined:
  • The volume is moved to the Scratch Category defined in Tape Manager.
  • The Tape Manager Expire Hold date for the volume is set to the current date.
  • The Tape Manager Expire Hold (XH) flag is set to H (hold) in the volume System Status (SSTAT) field.

The XH flag will prevent the volume from being used for scratch mounts until the Expire Hold period has ended. When expiration processing determines that the Expire Hold period has elapsed, the XH flag will be set to no-hold, the Expire Hold date will be "zeroed" (filled with 0's) and the volume will become available for scratch mounts.