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Thread: backup design

  1. #1
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    Unanswered: backup design

    Hi all,

    I am going to desingn a database of size 500gb(24/7).I don't know
    how to desing backup startegy.Pls explain?.

  2. #2
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    ensure no data is ever lost regardless of what happens

  3. #3
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    There's a whole Oracle manual (otn.oracle.com) devoted to the subject which is quite complete and that you must know perfectly if you want to avoid data loss (=immediate job loss), since the #1 responsibility of any DBA is to ensure proper backups and 100% recovery ...

    You will want to

    - run the database in ARCHIVELOG mode
    - archive the archived logs, perhaps on multiple disks or tapes
    - multiplex the redo logs on different physical disks
    - multiplex the control files on different disks
    - after any NOLOGGING operation, backup the tablespace that contains the object that were affected by the nologging operation.

    You will periodically (e.g. every night) make a backup of the datafiles (perhaps incremental) and then delete the old archived logs.

    These are the basics - in the backup&recovery guide there is much more information including scenarios.

    You probably want to use RMAN for a 24/7 database of 500G, or an equivalent product. It has very interesting features.

    My best advice: practice the backup - on a test machine, delete a datafile and try to restore it; than make the same for a redo log, a control file ... only way to be sure that your backup strategy works.

    HTH
    Al

  4. #4
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    >You will periodically (e.g. every night) make a backup of the datafiles
    > (perhaps incremental) and then delete the old archived logs.
    This bad, nonsensical advice. Within an Oracle DB every "data" file
    is updated with the latest SCN as transactions complete. I delete "old archived redo logfiles, only after I'm convinced that I have a known good & complete backup from which an actual restore has completed.
    Murphy is alive & well.

  5. #5
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    Originally posted by anacedent
    >You will periodically (e.g. every night) make a backup of the datafiles
    > (perhaps incremental) and then delete the old archived logs.
    This bad, nonsensical advice. Within an Oracle DB every "data" file
    is updated with the latest SCN as transactions complete. I delete "old archived redo logfiles, only after I'm convinced that I have a known good & complete backup from which an actual restore has completed.
    Murphy is alive & well.
    I meant that you cannot just make a backup of the datafiles today, and then archive the logs forever, without periodically making another backup. Say a datafile get lost after a month - you restore the datafile, start recovering the tablespace - and wait for hours for the archived logs to be applied, which is not acceptable in a 24x7 environment.


    You must periodically make a backup (i said daily, just as an example, obviously it depends on the write activity on the db); at this time the archived logs (those taken before the backup) are obsolete, and you can get rid of them (usually you get rid, since your disk/tape space is finite).

    You don't make this by hand, you do it automatically (best done using RMAN); obviously you must check the whole procedure, as i suggested at the end of my reply, in order to be sure that your backup will be restorable.

    Your backup strategy/routine could, after the (daily) backup, perform (again, automatically) a recover on another machine to check for backup corruption before getting rid of the old archived files, as you suggest - this can be part of the procedure - provided that you have another machine available. Or, you could have two or three backups (and the archived logs between them obviously) to fallback to in case the last is corrupted thanks to Mr Murphy. It depends on the resources you have available - your suggestion being one possible solution, not the only possible one.

    But, please note that I stated clearly that i was just giving the basic hints in the reply - not rewriting the whole manual, which i pointed the original poster to, or working out any possible variation and detail.

    bye
    Al

  6. #6
    Join Date
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    Re: backup design

    Originally posted by sudheer_ics
    Hi all,

    I am going to desingn a database of size 500gb(24/7).I don't know
    how to desing backup startegy.Pls explain?.
    Backup and Recovery Concepts Contents / Search / Index / PDF
    Backup and Recovery Documentation Online Roadmap Contents / Search / /
    http://otn.oracle.com/pls/db92/db92....emark=homepage
    Joel Pérez

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