Enlarging a Database Instance

Use

If you notice that the data area was defined too small when you created the database instance and are concerned that the data area may overflow, you can extend the data area while the database is in operation.

You must have sufficient storage space to do this; when you create a data volume, you simultaneously reserve the corresponding storage space for the database system.

During database operation, you can only add data volumes if the value you defined for MAXDATAVOLUMES is sufficiently large.

If this value is insufficient, you first have to raise the value for MAXDATAVOLUMES and start the database system again. You can then add data volumes while the database is in operation.

You can use the function for automatically extending the data area, which creates data volumes as soon as the database system has reached the defined fill level. You can also add data volumes manually.

To read the prerequisites, see Database Manager CLI, auto_extend, db_addvolume

See also:

Changing the Value of a Single Database Parameter

Concepts of the Database System, Volumes (Permanent Storage) “Data Volumes” section; see also Database Design

Scenario 1

You want the database system to extend the data area by one data volume whenever the fill level reaches 66%. The system should then create additional data volumes in the directory in which the last data volume that was defined is stored.

The last created data volume is of the type File.

Procedure

...

       1.      Call the Database Manager CLI in session mode, log on as operator OLEG with the password MONDAY, connect to the database instance DEMODB:

>dbmcli –u OLEG,MONDAY –d DEMODB

dbmcli on DEMODB>

       2.      Activate the function for automatic extension of the data area at a fill level of 66%:

dbmcli on DEMODB>auto_extend ON 66

OK

Result

You have activated the function for automatically extending the data area.

You can check this with auto_extend SHOW and display the value currently defined as the threshold value.

Scenario 2

You have noticed that the fill level of the data area of DEMODB is approaching 95%. The fill level you wish to achieve, however, is 50%.

Thus the system should add as many volumes as necessary to achieve a database area fill level of 50%.

Procedure

...

Call the Database Manager CLI, log on as operator OLEG with the password MONDAY, connect to the database instance DEMODB,

Extend the data area so as to reach a fill level of 50%:

>dbmcli –u OLEG,MONDAY –d DEMODB db_addvolume DATA –fd 50

OK

1

Result

To reach a fill level of 50%, the system has added one volume.

Scenario 3

As a precaution, you want to create a second data volume of type File for DEMODB. You want it to be the exact same size as the first data volume (32768 pages) and created with the name DISKD0002 in the same directory (C:\Documents and Settings\All Users\Application Data\sdb\data\DEMODB\data).

Procedure

       1.      Call the Database Manager CLI in session mode, log on as operator OLEG with the password MONDAY, connect to the database instance DEMODB:

>dbmcli –u OLEG,MONDAY –d DEMODB

OK

dbmcli on DEMODB>

       2.      Create the second data volume with the properties listed in the scenario:

dbmcli on demodb>db_addvolume DATA "C:\Documents and Settings\All Users\Application Data\sdb\data\DEMODB\data\DISKD0002" F 32768

OK

Result

You have created data volume DISKD0002 for database instance DEMODB.

You can display all data and log volumes as well as the paths to where they are stored using the DBM command param_getvolsall.