Tivoli Storage Manager for Windows: Administrator's Guide


Decreasing the Size of the Database or Recovery Log

You may want to delete database or recovery log volumes for a number of reasons. For example:

When you delete a database or recovery log volume, Tivoli Storage Manager tries to move data from the volume being deleted to other physical volumes in the database or recovery log.

To delete space, perform the following steps:

  1. Determine if you can delete one or more volumes ("Step 1: Determining If Volumes Can Be Deleted").
  2. Reduce the capacity of the database or recovery log to free existing space (Step 2: Reducing the Capacity of the Database or Recovery Log).
  3. Delete the volume ("Step 3: Deleting a Volume from the Database or Recovery Log").

Step 1: Determining If Volumes Can Be Deleted

To determine if volumes can be deleted from the database or recovery log, check the volume sizes and the amount of unused space. To check the sizes of the volumes in the database, enter:

query dbvolume format=detailed

The server displays the following type of information:

+--------------------------------------------------------------------------------+
|Volume Name (Copy 1): d:\dbvol\vol4                                             |
|         Copy Status: Sync'd                                                    |
|Volume Name (Copy 2):                                                           |
|         Copy Status: Undefined                                                 |
|Volume Name (Copy 3):                                                           |
|         Copy Status: Undefined                                                 |
|Available Space (MB): 24                                                        |
|Allocated Space (MB): 24                                                        |
|     Free Space (MB): 0                                                         |
+--------------------------------------------------------------------------------+

In this example, VOL1, VOL2, VOL3, and VOL4 each have 24MB of available space, and VOL5 has 100MB. To determine if there is enough unused space to delete one or more volumes, enter:

query db

The server displays the following type of report.

+--------------------------------------------------------------------------------+
|Available Assigned   Maximum   Maximum    Page     Total      Used %Util  Max.  |
|    Space Capacity Extension Reduction    Size     Pages     Pages       %Util  |
|     (MB)     (MB)      (MB)      (MB) (bytes)                                  |
|--------- -------- --------- --------- ------- --------- --------- ----- -----  |
|      196      196         0       176   4,096    50,176     4,755   9.5   9.5  |
+--------------------------------------------------------------------------------+

The Maximum Reduction field shows the assigned capacity not in use. In this example, you could reduce the database by up to 176MB. This is enough space to allow the deletion of VOL1, VOL2, VOL3, and VOL4.

If there is not enough space on the remaining volumes, allocate more space and define an additional volume, as described in Increasing the Size of the Database or Recovery Log and continue with Step 2: Reducing the Capacity of the Database or Recovery Log.

Step 2: Reducing the Capacity of the Database or Recovery Log

The database or recovery log capacity is reduced in 4MB increments. For example, based on the utilization of the database assume that VOL5 alone could contain all the data. To reduce the database by the amount of available space in VOL1 through VOL4, 96MB, enter:

reduce db 96

Reducing capacity is run as a background process and can take a long time. Issue a QUERY PROCESS command to check on the status of the process.

After reducing the database by 96MB, the assigned capacity is 100MB, and the maximum extension is 96MB, as shown in the following example:

+--------------------------------------------------------------------------------+
|Available Assigned   Maximum   Maximum    Page     Total      Used %Util  Max.  |
|    Space Capacity Extension Reduction    Size     Pages     Pages       %Util  |
|     (MB)     (MB)      (MB)      (MB) (bytes)                                  |
|--------- -------- --------- --------- ------- --------- --------- ----- -----  |
|      196      100        96        92   4,096    24,576        86   0.3   0.3  |
+--------------------------------------------------------------------------------+

Step 3: Deleting a Volume from the Database or Recovery Log

After you reduce the database or recovery log, use the smaller size for a few days. If the maximum utilization does not exceed 70%, you can delete the extra volumes.

Note:
You cannot delete volumes if there is not enough free space for the server to move data from the volume being deleted to other physical volumes in the database or recovery log.
In our example, you determined that you can delete the four 24MB volumes from the database. You have reduced the database by 96MB. To delete VOL1 through VOL4 from the database, enter:
delete dbvolume vol1
delete dbvolume vol2
delete dbvolume vol3
delete dbvolume vol4

The server moves data from the volumes being deleted to available space on other volumes, as shown in Figure 73.

Figure 73. Deleting Database Volumes



Deleting Database Volumes

After the data has been moved, these volumes are deleted from the server.


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