Tivoli Storage Manager for Windows: Administrator's Guide


How Tivoli Storage Manager Manages Space

Tivoli Storage Manager tracks all volumes defined to the database as one logical volume and all volumes defined to the recovery log as another logical volume. In Figure 68, the database consists of four volumes: VOL1 through VOL4, which the server tracks as a single logical volume.

Figure 68. A Server Database



A Server Database

To manage the database and recovery log effectively, you must understand the following concepts:

Available Space

Not all of the space that is allocated for the volumes of the database or of the recovery log can be used for database and recovery log information. The server subtracts 1MB from each physical volume for overhead. The remaining space is divided into 4MB partitions. For example, you allocate four 25MB volumes for the database. For the four volumes, 4MB are needed for overhead leaving 96MB of available space as shown in figure Figure 69:

Figure 69. An Example of Available Space



Available Space

Assigned Capacity

Assigned capacity is the available space that can be used for database or recovery log information. During installation, the assigned capacities of the database and recovery log match the available space. If you add volumes after installation, you increase your available space. However, to increase the assigned capacity, you must also extend the database or recovery log. See Step 2: Extending the Capacity of the Database or Recovery Log for details.

Utilization

Utilization is the percent of the assigned capacity in use at a specific time. Maximum percent utilized is the highest utilization since the statistics were reset. For example, an installation performs most backups after midnight. Figure 70 shows that utilization statistics for the recovery log were reset at 9 p.m. the previous evening and that the maximum utilization occurred at 12 a.m.

Figure 70. An Example of Recovery Log Utilization



Recovery Log Utilization

Unless many objects are deleted, the database maximum percent utilized is usually close to the utilization percentage.


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