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Administrator's Guide


How the Server Manages Storage

Through the server, you manage its storage -- the devices and media used to store client data. The server integrates the management of storage with the policies that you define for managing client data.

Tivoli Storage Manager Device Support

Tivoli Storage Manager supports the use of a variety of devices for server storage. A current list is available at the Tivoli Storage Manager Web site:

http://www.tivoli.com/support/storage_mgr/tivolimain.html

Tivoli Storage Manager represents physical storage devices and media with the following administrator-defined objects:

Device class
Each device is associated with a device class that specifies the device type and how the device manages its media.

Storage pools and volumes
A storage pool is a named collection of volumes that have the same media type. A storage pool is associated with a device class. For example, a 3490 tape storage pool contains only 3490 tape volumes. A storage pool volume is associated with a specific storage pool.

For details about device concepts, see Chapter 2, Introducing Storage Devices.

Migrating Data through the Storage Hierarchy

You can organize the server's storage pools into one or more hierarchical structures. This storage hierarchy allows flexibility in a number of ways. For example, you can set policy to have clients send their backup data to disks for faster backup operations, then later have the server automatically migrate the data to tape.

See Overview: The Storage Pool Hierarchy.

Removing Expired Data

Policy that you define controls when client data automatically expires from the Tivoli Storage Manager server. The expiration process is how the server implements the policy.

For example, you have a backup policy that specifies that three versions of a file be kept. File A is created on the client, and backed up. Over time, the user changes file A, and three versions of the file are backed up to the server. Then the user changes file A again. When the next incremental backup occurs, a fourth version of file A is stored, and the oldest of the four versions is eligible for expiration.

To remove data that is eligible for expiration, a server expiration process marks data as expired and deletes metadata for the expired data from the database. The space occupied by the expired data is then available for new data.

You control the frequency of the expiration process by using a server option, or you can start the expiration processing by command or scheduled command.

See Running Expiration Processing to Delete Expired Files.

Reclaiming Media for Reuse

As server policies automatically expire data, the media where the data is stored accumulates unused space. Other products might require you to implement a tape rotation scheme that allows you to reuse the media only when all data on the media has expired. The Tivoli Storage Manager server implements a different process, called reclamation, that allows you to reuse media without traditional tape rotation.

Reclamation is a server process that automatically defragments media by consolidating unexpired data onto other media when the free space on media reaches a defined level. The reclaimed media can then be used again by the server. Reclaiming media allows the automated circulation of media through the storage management process. Use of reclamation can help minimize the number of media that you need to have available.


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