Differential Backup

  • I am a little confused as to what is going on with my diff backups. I run the following statement Sunday morning to do a FULL backup resulting in 21GBs backup set. VERY little processing goes on during the course of Sunday into Monday morning.

    BACKUP DATABASE [database] TO  DISK = N'M:\backup\database.bak' WITH  INIT ,  NOUNLOAD ,  NAME = N'database backup Full',  NOSKIP ,  STATS = 10,  NOFORMAT

    Monday morning I run the following command against the same db resulting in a 19GBs differential backup. How could that be? Isn't the differential backup the difference from the time the full backup ran till the running of the differential?

    BACKUP DATABASE [database] TO  DISK = N'M:\backup\database.bak' WITH  INIT ,  NOUNLOAD ,  DIFFERENTIAL ,  NAME = N'database backup Diff Mon',  NOSKIP ,  STATS = 10,  NOFORMAT

     

     

  • Are you rebuilding indexes on Sunday?  That would cause a lot of changes to extents as stuff is moved around in the data file.

    Greg

    Greg

  • Oversite on my part. That would explain a lot. So the rest of the weeks differential backups will be at least 19GBs and increase with whatever data changes were made?

  • Yes, if you do full backups only on Sunday morning.  Maybe you could schedule your reindexing to occur before the weekly full backup?

    Greg

    Greg

  • Mike,

    May be you could place your database in the simple recovery mode before reindexing. Once reindexing is done you put it back in full recovery mode and do the full backup...

     

     

     

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