Changing Database Configuration Parameters

Objectives

After completing this lesson, you will be able to:

  • Configure the SAP HANA database

SAP HANA Database Configuration Parameters

The properties of an SAP HANA database system are defined by the parameters in its configuration files. The configuration files are separated into sections; these sections bundle parameters of the same category.

Opening the System Configuration Tool

You can display and change parameters using the SAP HANA cockpit through the Database Configuration app. To change the parameters of configuration files, you require the system privilege INIFILE ADMIN.

Note

Do not change parameters directly in the configuration files on the operating system level.

Finding Configuration Parameters Using Search

SAP HANA has many configuration files and parameters. Therefore, to find a parameter easily in the parameter structure, use the Search function.

In the Search field, enter the name of a parameter, or few characters of a parameter, and select Enter on your keyboard.

If you upgrade to a new version of SAP HANA, the newest parameter settings based on the newest experiences are included automatically, but your own changes remain unchanged.

You can easily distinguish between parameters that still have their default value or have been changed. The pencil icon beside a parameter is the indicator of a change.

Furthermore, you can take configuration snapshots of the parameters of your database. These snapshots reflect the configuration of a database at the point in time when it was created, and can be compared with the current configuration or another previously generated snapshot. This is an easy way to identify configuration changes over time.

Additionally, the View Change History button shows, when, which, and by whom database parameters were changed in the past.

Changing of Configuration Parameter Values with SAP HANA Cockpit

In the list, you can find the parameters that you searched for. Now, you can change the parameter by choosing the plus (+) button in front of the parameter, or the Override Value button at the end of the line.

Parameter changes are done to adopt specific customer requirements. For this, changes to configuration parameters of the SAP HANA database, the underlying operating system, ports, and further areas are necessary.

Caution

Only change the configuration parameters of the SAP HANA database if these changes are recommended in the SAP documentation, SAP Notes, or by SAP employees (for example, consulting, development, and support).

To guarantee optimal performance and the highest stability, SAP hardware and technology partners can deliver SAP HANA systems with settings that deviate from the standard. For more information see, SAP Note 1730999: Configuration changes to SAP HANA system.

Changing Parameter Values in SAP HANA Cockpit

After choosing the plus (+) or Override Value button, a dialog box appears where you can enter the parameter values.

When using the Database Configuration app in the SAP HANA cockpit, there is a clearly defined hierarchy of parameter values, based on different so-called layers, according to the evaluation sequence. At first, the layer DEFAULT is taken into account, which comes from the SAP HANA kernel. Then, at the second place, layer SYSTEM is evaluated, which would inherit the detected value to all tenant databases. But, if the third layer DATABASE brings another value for a single database, the respective value will be applied. The fourth (and last) layer HOST can only be set for a limited number of parameters and would overwrite even the value delivered with the former database layer. The layer HOST only makes sense to be used in a multi-host (scale-out) environment.

Furthermore, the user interface for parameter changes in the SAP HANA cockpit provides some useful features (see the numbers in the figure, Changing Parameter Values in SAP HANA Cockpit):

  • 1+5: Database restart indicator: visible in case of editing a static parameter

  • 2+3: Value validation: the input of the value field is checked according to the type of the field

  • 4: Restore default values

  • 6: Hierarchy of layers

To edit or restore a changed configuration parameter value back to its default value, choose the Edit Parameter (pencil) button next to the value. If you choose the Restore Default option, the change is reverted. But don't forget to save when done.

Note

Be aware that the layer DEFAULT is visible as part of the list of the Database Configuration app and cannot be seen as an explicit layer when already using the Override Values dialog.

Configuration Files

SAP HANA stores the configuration parameters in configuration files on the operating system level. During the start of the SAP HANA database, these files are read and the changes are activated.

Configuration files (INI files) are only created in the file system if customer-specific changes are made to them after installation. If no customer-specific changes have been made, these directories remain empty.

The configuration files are located in the following directories:

  • Default configurations: /usr/sap/<SID>/HDB<instance number>/exe/config

    The default value for the property (read-only).

  • System configurations: /usr/sap/<SID>/SYS/global/hdb/custom/config

    The system-specific value for the property (configurable in the system database). If a system-specific value is not configured for a property, the default value applies.

  • Tenant-specific configurations: /usr/sap/<SID>/SYS/global/hdb/custom/config/DB_<tenant-name>

    The database-specific value for the property (configurable in the system or tenant database). For some properties, it is possible to set database-specific values. If a database-specific value is not configured, the system-specific or host-specific value applies.

  • Host-specific configurations: /usr/sap/<SID>/HDB<instance number>/<host name>

    The host-specific value for the property (configurable in the system database). For some properties, it is possible to set host-specific values for multiple-host systems. If a host-specific value is not configured for a property that can be set at host level, the system-specific value applies.

Note

For more information, see the following SAP Notes:

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