Database backup

  • Hi,

    I have some issue regarding database backup.

    I am taking backup of full backup of my database every 2 hour.

    Differential backup every 1 hour.

    Transaction log backup every 15 min.

    If I dont do anything in my database, then backup file should remain condtant each time. But each time transaction log backup is growing. In the maintenance plan I have mentioned as the transaction log file as overwrite. Can anyone tell me what is the problem?

    Ryan
    //All our dreams can come true, if we have the courage to pursue them//

  • Hang on.

    You're backing the transaction log up every 15 min, writing to the same file and specifying overwrite? Is that correct?

    Why full backups ever 2 hours? That's awfully frequent, especially with a diff every hour.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • You transaction log backup should not be growing if you are not changing data. If it is, I can only assume that transactions are being added to the database, inserts, updates, deletes, something.

    How are you specifying the backups?

  • This is testing purpose in testing region. But actually it wiil be one full back up per day, differential back every 4 hour and transaction log every 1 hour. Actual problem is to the growing size of the transaction log though there is no transaction is performed. Two options are available in back up 1. Append and 2. overwrite to the file.

    So my question is why the transaction log is growing with any of the option? Full backup file and differential back up file is not grwing for the same option overwrite when no transaction is performed.

    Ryan
    //All our dreams can come true, if we have the courage to pursue them//

  • One thing I would like to get clear.

    Are you backing up the transaction log to the same file every time?

    Do you have the overwrite option specified?

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • Are you backing up to a device - or a file? How is this being selected?

    What Gail was trying to get at is that overwriting an existing file destroys any maintenance plan you setup. What good is a transaction log backup if it only contains the currently backed up transaction log? You won't be able to restore the system because you are now missing the previous transaction log backup.

    If you are also overwriting the differential backup - you have the same problem. As well as overwriting the full. To understand better, what is going to happen if you have to restore the system to 10:50am, but your differential backup ran at 11:00am and overwrote the previous differential backup that was run at 10:00am? Add in the fact that you have overwritten the transaction log backups and you don't have a method of restoring to that point in time. The best you can do is restore to the latest differential.

    Jeffrey Williams
    “We are all faced with a series of great opportunities brilliantly disguised as impossible situations.”

    ― Charles R. Swindoll

    How to post questions to get better answers faster
    Managing Transaction Logs

  • Jeffrey Williams (4/24/2009)


    What Gail was trying to get at is that overwriting an existing file destroys any maintenance plan you setup.

    Note to self. Get to the point..., 😉

    The best you can do is restore to the latest differential.

    Providing that the full backup that was the base for that diff is still available.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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