differential backup vs. log backup

  • Hello every body,

    I have a stupid question but I will much apprciated if some body explain to me the different between differential backup and log backup. as I understand that if you have full back up and all the log from the full back up until the point when server crash or fail, then you can restore the system!

    I think and not sure that differential backup is just combining  all the log files in one back which occur between full back up and differential back. is that right? 

     

    Thank you

  • A differential backup contains all changes made since the last full backup.  Thus, in a way, you could say that it contains 'all the log files in one back which occur between full back up and differential back'.

    The advantage is you only need to restore two files during the restore (full and differential backup files).  One disadvantage is that you cannot restore to a point in time as you can for a trx log backup.  File sizes and time taken to backup may also vary greatly, depending on the amount of inserts/updates in your database.

    SQL BAK Explorer - read SQL Server backup file details without SQL Server.
    Supports backup files created with SQL Server 2005 up to SQL Server 2017.

  • I'll add that you can also restore log backups after restoring a differential, which can save a lot of time when restoring.  

    For example, if you do a full backup at 4:00 AM, log backups every hour, and a differential at Noon, and you want to recover to 3:00 PM because of a crash, you can restore the full, the differential and 3 log backups instead of the full and all of the log backups since 4:00 AM.

    Greg

     

     

    Greg

  • My only real gripe about differential backups is that they aren't included in the database maintenance plan wizard.  I guess I do need to install yukon and see if that has changed...

  • Hello every body,

    First of all thank you for your response and for helping me understand the different between Diff and log backup. However, I still have one more question. Does differental back up will have . dif as fill extension or still will use .bak as file extension. Your reposne is much apprciated

     

     

  • You can actually name a backup file anything you want.  I've seen examples where full backups go to a file with a .ful extension and differential backkups go to a file with a .dif extension.

    Greg

    Greg

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