Tivoli Storage Manager for Windows: Administrator's Guide


Notes on Operations

Administrators should be aware of the following when using magnetic disk devices with TSM.

Using Cache

When you define a storage pool that uses disk random access volumes, you can choose to enable or disable cache. When you use cache, a copy of the file remains on disk storage even after the file has been migrated to the next pool in the storage hierarchy (for example, to tape). The file remains in cache until the space it occupies is needed to store new files.

Using cache can improve how fast a frequently accessed file is retrieved. Faster retrieval can be important for clients storing space-managed files. If the file needs to be accessed, the copy in cache can be used rather than the copy on tape. However, using cache can degrade the performance of client backup operations and increase the space needed for the TSM database. For more information, see Using Cache on Disk Storage Pools.

Freeing Space on Disk

As client files expire, the space they occupy is not freed for other uses until you run expiration processing on the server.

Expiration processing deletes from the TSM database information about any client files that are no longer valid according to the policies you have set. For example, suppose four backup versions of a file exist in server storage, and only three versions are allowed in the backup policy (the management class) for the file. Expiration processing deletes information about the oldest of the four versions of the file. The space that the file occupied in the storage pool becomes available for reuse.

You can run expiration processing automatically or by command. See Running Expiration Processing to Delete Expired Files.

Specifying Scratch FILE Volumes

You can specify a maximum number of scratch volumes for a storage pool that has a FILE device type. When the server needs a new volume, the server automatically creates a file that is a scratch volume, up to the number you specify. When scratch volumes used in storage pools become empty, the files are deleted.

Using FILE Volumes for Database Backups and Export Operations

When you back up the database or export server information, the server records information about the volumes used for these operations in the volume history. The server will not allow you to reuse these volumes until you delete the volume information from the volume history. To reuse volumes that have previously been used for database backup or export, use the DELETE VOLHISTORY command. For information about the volume history and volume history files, see Saving the Volume History File.

Note:
If your server is licensed for the Tivoli Disaster Recovery Manager (DRM) product, the volume information is automatically deleted during MOVE DRMEDIA command processing. For additional information about DRM, see Chapter 24, Using Tivoli Disaster Recovery Manager.


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