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 the log segments is defined by the general database parameter LOG_SEGMENT_SIZE. Their size is independent of the size of the individual log volumes, but must not be bigger than the total size of the log volumes. The size should be selected so that, when a log segment is backed up, enough space remains in the log area to ensure that the changes taking place at the time can be recorded.
User-Defined Value |
Log Segment Sizes Used by the System |
No definition of log segment size (LOG_SEGMENT_SIZE = 0) |
One-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 value defined for LOG_SEGMENT_SIZE |
The log segment > 50% of the total log area. |
50% of the log area |