Gaps in the Restore Process
When reviewing records in the Master.dbo.bts_LogShippingHistory table, you may observe gaps in restored sets. This can occur for several reasons. However, the stability of the destination system can be restored even when gaps have occurred. A gap must be followed by a restore of a full backup set to repair the destination environment. If a gap is not followed by a full backup set restore, the destination environment is not stable and cannot be restored in a consistent state.
Note
Full backups are only restored to initially create the database and to repair problems in the log history backup chain. As long as a problem does not occur with a restore, full backup sets are not restored, because they do not participate in the log backup chain.