Data backup in WinCC OA

In WinCC OA we distinguish between the following kinds of data that can be backed up:

  • Current project status DB backup Project backup


    To improve performance with historical alert queries (Alert Screen) you can limit the number of additional values (_add_value) of alerts that are queried. This does not affect or limit the number of additional values that are stored.

    To specify the maximum number of additional values to be queried, set the parameter "max_add_value" to a value from 1 to 32 in the ARC_CONFIG table. Values outside the range 1 to 32 are ignored. If the _add_values ​​are not queried, these views are not used. By default all 32 default values will be queried.


    Regarding the behavior of alertSetWait for historical alerts in NGA/RDB projects consider the following:

    There is no indication of whether the operation was done or if it was successfully done when alertSetWait finished executing. In case of an invalid alert time no error message is printed to the log file and the return value of alertSetWait does not indicate it either.

    In case of a valid alert time it is still not guaranteed that the value is already persistent in the database when alertSetWait finishes executing.

History values

This backup stores completed archive records containing history data (e.g. all hourly values from 1.4 - 30.4). These archive records are deleted from the disk after a set period and can be restored from the backup if required.

Using the History DB

Each backup per archive can be configured differently.

The time for backing up can be set separately from the time of changing the archive record. For example, it makes sense to perform monthly backups (perhaps a few days later) if you change the archive record on a monthly basis. The interval between changing the archive record and backing up and the number of "archive records" of correction values remaining on the disk determine how long archive records are left not backed up after being completed. Correction values entered in this interval are included in the backup.

  1. On the SysMgm/Database/Database/Select archive/Configuration/Time panel select times for automatic record change (see Create and configure archive).

  2. On the SysMgm/Database/Database/Select archive/Configuration/Backup panel enter the target path and devices for backups (see Create and configure archive).


You must perform these two steps for every single archive!

  1. Please see Swap out archive for details on how to perform a manual archive change and how to swap archives back in.

Usually the DB works transaction oriented, i.e. only consistent data are saved in archives. During initialization the value archive checks the records and tries to repair the record in the case of a defect. In some cases, as power failure, disk failures, ... the data can be destroyed (e.g. file size is 0), these failures cannot be eliminated. For this case the tool WCCOAtoolRepairDb creates automatically a new empty record.

History alarms (RAIMA database)

Here history alarms are swapped out.

  1. Adjust the settings for your alarm database on the Archive control panel under SysMgm/Database/Alarms.

Current project status (= Online backup)

DB backup

This backup stores the current project data such as incomplete archive records, last values,

the configuration database and other database contents required to reload the system following a crash (e.g. due to hard disk failure).

Depending on the project configuration (redundant or not) and the importance of the current data, you should perform this backup on a weekly or daily basis. It is advisable to enable the "Backup all not archived HDB datasets" option on the Backup panel (see Configuring backups). This also backups records not swapped out!

Project backup

This backup stores the complete project, except for the database. This backup also stores ASCII manager files that allow you to "restore" the project, albeit without history data.


You can only start this backup manually. It is advisable to perform this backup after changing any parameters.

How to backup your data

  1. You can adjust the settings for your backups on the SysMgm/Database/Online backup panel (see Service panels of online backup equipment operational panel).

  2. You can configure the time, medium, etc. for backups on the Configuration tab (see Configuring backups).

  3. Start the database backup (see Starting backup of the database), containing the configuration information and history, on the DB tab.

  4. Start backup of configuration of your project (see Starting backup of the project) on the Configuration tab. The database is not backed up but rather all file-bound data such as panels, scripts, etc.


Make sure that you have set the times correctly for all three backups. Time conflicts (overlap) must not occur, particularly when using DAT tapes!


It is possible to save combinations of these backups on one DAT device.