In SAP HANA with log mode "normal", log backups are triggered automatically to ensure the log volume does not fill up and to enable point-in-time recovery. The system initiates a log backup under two primary automatic conditions: first, when a log segment in the log volume becomes full, it must be backed up before it can be overwritten. Second, a configurable timeout (logbackuptimeouts) triggers a log backup if no backup has occurred within that specified interval, ensuring regular backups even during periods of low transaction activity.

A. When a commit occurs: A commit operation flushes the in-memory log buffer to the on-disk log segment. It does not trigger a log backup to the backup destination.

B. When the log buffer is full: A full log buffer also triggers a flush to the on-disk log segment to free up memory. This is not a trigger for the log backup process itself.

1. SAP HANA Administration Guide for SAP HANA Platform 2.0 SPS 07

Section: Log Backups.

Reference Text: "Log backups are performed automatically. A log backup is triggered when a log segment is full or when the configurable log backup timeout has been reached." This statement directly supports answers D and C.

2. SAP HANA Administration Guide for SAP HANA Platform 2.0 SPS 07

Section: Log Backup Settings.

Reference Text: "The parameter logbackuptimeouts in the persistence section of the global.ini file specifies a timeout for log backups in seconds. The default setting is 900 seconds (15 minutes)." This confirms the time threshold mechanism (Answer C).

3. SAP HANA Administration Guide for SAP HANA Platform 2.0 SPS 07

Section: Log Area.

Reference Text: "Before a log segment can be reused

it must be backed up. If log backups are not performed

the log area grows until the file system is full." This explains why a full log segment triggers a backup (Answer D).