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Administrator's Guide


How Tivoli Storage Manager Uses and Reuses Removable Media

Tivoli Storage Manager allows you to control how removable media are used and reused. After Tivoli Storage Manager selects an available medium, that medium is used and eventually reclaimed according to its associated policy.

Tivoli Storage Manager manages the data on the media, but you manage the media itself, or you can use a removable media manager. Regardless of the method used, managing media involves creating a policy to expire data after a certain period of time or under certain conditions, move valid data onto new media, and reuse the empty media.

In addition to information about storage pool volumes, the volume history contains information about tapes used for database backups and exports (for disaster recovery purposes). The process for reusing these tapes is slightly different from the process for reusing tapes containing client data backups.

Figure 5 shows a typical life cycle for removable media. The numbers (such as (1)) refer to numbers in the figure.

Figure 5. Simplified View of the Life Cycle of a Tape

Simplified View of the Life Cycle of a Tape

  1. You label (1) and check in (2) the media. Checking media into a manual library simply means storing them (for example, on shelves). Checking media into an automated library involves adding them to the library volume inventory.

    See Labeling Removable Media Volumes.

  2. If you plan to define volumes to a storage pool associated with a device, you should check in the volume with its status specified as private. Use of scratch volumes is more convenient in most cases.
  3. A client sends data to the server for backup, archive, or space management. The server stores the client data on the volume. Which volume the server selects (3) depends on:

    See Figure 6.

    Figure 6. How Tivoli Storage Manager Affects Media Use

    How Tivoli Storage Manager Affects Media Use

  4. The data on a volume changes over time as a result of:

    If the volume becomes empty because all valid data either expires or is moved to another volume, the volume is available for reuse (unless a time delay has been specified for the storage pool). The empty volume becomes a scratch volume if it was initially a scratch volume. The volume starts again at step 3.

  5. You determine when the media has reached its end of life.

    For volumes that you defined (private volumes), check the statistics on the volumes by querying the database. The statistics include the number of write passes on a volume (compare with the number of write passes recommended by the manufacturer) and the number of errors on the volume.

    You must move any valid data off a volume that has reached end of life. Then, if the volume is in an automated library, check out the volume from the library. If the volume is not a scratch volume, delete the volume from the database.


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