In log backups, the log area is not saved as a whole. Instead, it is saved in backup units, called log segments.
The size of a log segment is defined by the general database parameter LOG_SEGMENT_SIZE and has the following meaning:
· It determines the size of the parts into which the log entries are saved during interactive log backups.
· It also determines the threshold value for automatic log backups at which the backup of the log area is triggered.
The size of the log segment depends on the size of the individual log volumes and must not be greater than the sum of all log volumes. The size should be selected so that enough space remains in the log area during the backup of a log segments to ensure that the changes taking place at the time can also be recorded.
User-defined value |
Log segment sizes used by the system |
No definition of log segment size (LOG_SEGMENT_SIZE = 0) |
A third of the total log area. |
The log segment size in pages is smaller than or the same as 50% of the total log area. |
The defined value for LOG_SEGMENT_SIZE. |
The log segment > 50% of the total log area. |
50% of the log area. |