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  1. #1
    Join Date
    Aug 2013

    Unanswered: Db2 incremental backup

    hi All,
    Just want to find out what's the difference between incremental delta backup and without configured for incremental ? Without Culmulative or delta, I just use one full backup + all the logs since last full backup. Similarly, when restore for incremental delta. it also require full db backup + delta + logs.. to recover full db.

    the only benefits using incremental backup is performance, with incremental delta recoveries I can perform faster than recover using just logs, probably delta had already consolidate all changes whereas when recovery logs, it will take more time to replay. Am I interpret correctly ?

    Last edited by ckwan123; 07-06-14 at 19:54.

  2. #2
    Join Date
    Apr 2006
    Provided Answers: 11
    completely wrong
    advantage of incr or incr delta is size of backup image
    the time is similar as it scans all pages to see if the page has been flagged as modified
    restore can take longer : start restore with last backup - full backup and intermediate needed backup and end with last backup - rollforward
    see infocenter for all details
    Best Regards, Guy Przytula
    Database Software Consultant
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  3. #3
    Join Date
    Jul 2013
    Moscow, Russia
    Provided Answers: 55
    I would not say that ckwan123's statement about speed of recovery is wrong.
    If you have the following backups sequence:
    Time Type
    ____ _____
    TS1  Full
    TS2  Delta
    TS3  Delta
    - restoring Full + 2 Deltas + rolling forward from TS3 to end of logs
    should be significantly faster than
    - restoring Full + rolling forward from TS1 to end of logs

    i.e. restoring 2 Deltas should be significantly faster than rolling forward from TS1 to TS3.

  4. #4
    Join Date
    Sep 2013
    both benefits are there, in terms of backup image size and restore speed in some scenarios.

  5. #5
    Join Date
    Aug 2013
    Thanks guys, I believe there must be a reason why delta was introduced if the performance is same right ? otherwise I just replay all the logs will do. Anyone can explain deeper how it achieve better performance maybe internally how it works. Thanks.

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