The SAP HANA system logs all the transactions that change application data or the database catalog in log entries and stores them in log area. It uses these log entries in log area to roll back or repeat SQL statements. The log files are available in HANA system and can be accessed via HANA studio on Diagnosis files page under Administrator editor.
During a log backup process, only the actual data of the log segments is written from the log area to service-specific log backup files or to a third-party backup tool.
After a system failure, you may need to redo log entries from log backups to restore the database to the desired state.
If a database service with persistence stops, it is important to ensure that it is restarted, otherwise recovery will be possible only to a point before service is stopped.
Configuring Log backup Timeout
The log backup timeout determines the interval at which the log segments are backed up if a commit has taken place in this interval. You can configure the log backup timeout using the Backup Console in SAP HANA studio −
You can also configure the log_backup_timeout_s interval in the global.ini configuration file.
The log backup to the “File” and backup mode “NORMAL” are the default settings for the automatic log backup function after installation of SAP HANA system. Automatic log backup only works if at least one complete data backup has been performed.
Once the first complete data backup has been performed, the automatic log backup function is active. SAP HANA studio can be used to enable/disable the automatic log backup function. It is recommended to keep automatic log backup enabled otherwise log area will continue to fill. A full log area can result a database freeze in HANA system.
You can also change the enable_auto_log_backup parameter in the persistence section of the global.ini configuration file.