RMAN nocatalog
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  1. #1
    Join Date
    Oct 2007
    Posts
    114

    RMAN nocatalog

    Hi Friends,

    I have been backing up my database with RMAN nocatalog and it was fine.
    What is the advantage of RMAN with catalog pls? What I can see is a disadvantage because you need to have another database for the catalog.
    So you have also to protect it by backup it up with rman too? What will happen if the catalog crashes and you have no backup?

    Thanks a lot

  2. #2
    Join Date
    Aug 2007
    Location
    Cyberjaya,kuala lumpur
    Posts
    340
    1)A recovery catalog is a schema stored in a database that tracks backups and stores scripts for use in RMAN backup.
    2) Yes.. We have to protect the catalog database.if the catalog database is crashed you will lost the backup informations you kept in the catalog.if you have the backup of the catalog database you can restore the database.

  3. #3
    Join Date
    Nov 2001
    Posts
    335
    If you use a catalog then your backup informatin stored in 2 places, control file and catalog. If you lose a catalog you still have you control file (some limitations on how far back you can go will apply). If you lose you control file , you still have a catalog and will be able to restore a control file.
    If you do NOT have a catalog and lost your controlfiles, you should look for another job because most likely you will be fired.
    One, who thinks that the other one who thinks that know and does not know, does not know either!

  4. #4
    Join Date
    Oct 2007
    Posts
    114
    Thanks New Friend, Just saw ur ID here

    I'm a little confused about control files, how often do u backup the control files? if I have weekly backup of control files will I be able to use the week old control file if the current is lost?

    By the way in my RMAN backup the control file is also included, how can I lose the control files if it is being backed up?


    Thanks
    Last edited by reeshe; 07-11-2008 at 11:08 AM.

  5. #5
    Join Date
    Nov 2001
    Posts
    335
    If you lose all your live control files , your back info does not exists because it is stored in the very same control files that you just lost and in case u did not have a catalog you can not recover. If you do have a catalog, you can recover your controlfile, mount database and proceed with the database recovery.
    This is classic interview question, you would not pass !
    One, who thinks that the other one who thinks that know and does not know, does not know either!

  6. #6
    Join Date
    Sep 2002
    Location
    England
    Posts
    7,333
    can not recover? - what utter utter rubbish

  7. #7
    Join Date
    Apr 2003
    Location
    Pune,Maharashtra. India.
    Posts
    245
    I think you can recover from control file loss in no catalog mode provided you have configured "controlfile autobackup on"

    Please see "Table 2-25 RESTORE CONTROLFILE Scenarios" table from below link.
    http://download-west.oracle.com/docs...rcmsynta46.htm
    Rgds
    Parag

  8. #8
    Join Date
    Nov 2001
    Posts
    335
    Quote Originally Posted by paragp1981
    I think you can recover from control file loss in no catalog mode provided you have configured "controlfile autobackup on"

    Please see "Table 2-25 RESTORE CONTROLFILE Scenarios" table from below link.
    http://download-west.oracle.com/docs...rcmsynta46.htm
    Yes, you can restore from autobackup. I missed that. But what if autobackup location is gone too? Imagine you have all your rman backups sitting on the tape(netbackup or whatever other tsm ) and no controlfile! How would you restore your database?
    One, who thinks that the other one who thinks that know and does not know, does not know either!

  9. #9
    Join Date
    Jan 2001
    Posts
    2,828
    Hi

    The trick is to know the dbid and restore the controlfile from your tape backups

    Code:
    rman target /
    set dbid 
    startup nomount;
    run
    {
    allocate channel ch1sbt_tape type sbt;
    set controlfile autobackup format for device type sbt to
    'path_to_controlfile/%F'; 
    restore controlfile from autobackup;
    release channel ch1_tape;
    }
    You need to store the dbid somewhere otherwise i am afraid you are lost.

    regards
    Hrishy

  10. #10
    Join Date
    Sep 2002
    Location
    England
    Posts
    7,333
    Quote Originally Posted by hrishy
    Hi

    The trick is to know the dbid and restore the controlfile from your tape backups
    It's not a trick - its a fully documented, fully supported method of recovery

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