Activating or Deactivating the Dynamic Adjustment of the Data Area

Prerequisites

You are logged on to the database as the database system administrator or as a DBM operator with server authorization for accessing database parameters or utility sessions (see Glossary, Server Permission).
The installation-specific X server is running.
The maximum number of data volumes that you configured with database parameter MaxDataVolumes has not been reached yet.

A separate event task is required for this function. Make sure that the values of the FloatingServiceTasks and PreservedEventTasks database parameters are large enough (see Changing Database Parameters).
The last data volume that you added before activating the function must be of type FILE.

Note that the system can only remove data volumes of the FILE type using this function.

Context

The data of a database is permanently stored in the data volumes (data area).

Caution

If the data area of a database is full, the database stops working.

You can activate the dynamic adjustment of the data area size to ensure that the fill level of a database at any time does not fall below a defined value and not raise beyond another defined value. This way you make sure that the disk space is economically used and that the database cannot run out of capacity.

Automatic extension of the data area: The system adds new data volumes when the fill level of the data area exceeds a specified limit. This function is activated by default (maximum fill level of 90%).
Automatic shrinking of the data area: This function is deactivated by default. If the function is activated the system automatically checks whether a data volume can be deleted when the fill level of the data area falls below the specified value. It deletes surplus volumes if the following conditions apply:
- The specified percentage for the fill level is met or the specified number of empty data volumes is left over after the data area was shrunk.
- The resulting fill level does not exceed the fill level specified for the data area extension reduced by the buffer size.
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Recommendation
Only use this function if your database has multiple data volumes and the volumes have roughly the same size.

Note that you can also add or delete data volumes manually (see Adding or Deleting Data Volumes).

Procedure

Activating Dynamic Data Area Adjustment

Select the database in the explorer tree.
In the context menu of the database, choose Administration.
Open the Overview tab page.
Choose Dynamic Data Area Adjustment.

Select whether you want to activate automatic Data Area Extension only, or both automatic Data Area Extension and Data Area Shrinkage.

Option	Description
Fill Level	Fill level at which the system is to add a new data volume

Option	Description
Fill Level	Target fill level when shrinking the data area
Reserved Empty Volumes	Number of the empty volumes to remain when shrinking the data area. Note This is only an arithmetic value. It corresponds to the average size of a data volume in this database calculated by dividing the reserved data area by the number of available data volumes.
Buffer Size Buffer Percentage Buffer Empty Volumes	Buffer size: Difference between the thresholds for the extending and shrinking the data area (in percent) Number of empty volumes that is to remain after volumes were deleted

Option

Description

Fill Level

Target fill level when shrinking the data area

Reserved Empty Volumes

Number of the empty volumes to remain when shrinking the data area.

Note

This is only an arithmetic value. It corresponds to the average size of a data volume in this database calculated by dividing the reserved data area by the number of available data volumes.

Buffer Size

Buffer Percentage
Buffer Empty Volumes

Buffer size:

Difference between the thresholds for the extending and shrinking the data area (in percent)
Number of empty volumes that is to remain after volumes were deleted

Choose Activate.

Deactivating Dynamic Data Area Adjustment
1. Select the database in the explorer tree.
2. In the context menu of the database, choose Administration.
3. Open the Overview tab page.
4. Choose Dynamic Data Area Adjustment.
5. Select whether you want to deactivate both automatic Data Area Extension and Shrinkage, or only one of them.
6. Choose Deactivate.

Next Steps

Concepts of the Database System,