Consistency error due to differential bitmap out-of-sync

Today while working on the backup check I have noticed the checkdb step has got failed in the fullbackup job. I would like to know the reason why it has got failed, so started checking it and the history showed the hint as like data modified is not marked as modified in the differential backup bitmap.

So running the DBCC CHECKDB('RapidApplication_Test') with Physical_only gave me a result as shown below.

The detailed cause of this error is shown below

 

Cause of the error

We will just have a look at the background, differential bitmaps are used to keep track of which extents have been modified since the last full backup. A differential backup contains all those pages changed since the last full backup.

The page specified has a log sequence number (LSN) that is higher than the differential reference LSN in the BackupManager of the database or the differential base LSN in the file control block of the file, whichever is more recent. However, the page is not marked as changed in the differential backup bitmap.

It can be due to Hardware Failure, I/O error etc... In my cause that day the storage & wintel team was doing some change related to the hardware so that could be the reason for it.

Fix

Since the error gave me a hint about differential bitmap out-of-sync and also there was no other error reported in Checkdb so just taken the Fullbackup by thinking this will reset the differntial bitmap flag. Backup completed Successfully and thought of checking the result of of checkdb, Kudos!! got a clean result.

Target attained then started looking for the next task to work on.