Recovery after disaster
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Thread: Recovery after disaster

  1. #1
    Join Date
    Aug 2000
    Location
    Belgium
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    Question

    Hi all,

    I have a question about recovery of a db after a complete system crash.

    Let assume I have had a complete system failure.
    All disks are unreadable.

    I have :
    1) a offline backup of the db. ( datafiles/redolog/controlfile )
    2) all the archived log file generated after the offline backup.

    Can I make my db up to date using the offline backup, and the archived log files ???

    Gert

  2. #2
    Join Date
    Jul 2000
    Posts
    53
    Sorry, No!

    Not if all disks are lost as you will not be able to roll forward to the newer scn numbers that the archive logs contain.

    Regards,

    Steve
    Steve

  3. #3
    Join Date
    Jun 2000
    Location
    Madrid, Spain
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    I would say yes if we recreate the controlfile and recover the database with backup controlfile option.

  4. #4
    Join Date
    Jun 2000
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    deggzy you can rollforward with recover database until cancel backup controlfile option, this would ask you for archive logs until you say cancel, the recovery would stop there and recover until last archive log. I have tried this several times and it works. (with only datafiles and archive log files I was able to recover until latest archive log and open the database. I didnt even have any backup of redologs and controlfiles)

  5. #5
    Join Date
    Aug 2000
    Location
    Belgium
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    Smile

    Yes, it works. :-))

    I restored the offline backup. ( datafiles / redo logs / controlfiles )

    startup mount
    recover database
    --> message says no recovery is needed
    recover database until cancel using backup controlfile
    --> oracle looks at the last archived log in the controlfile, and generates the following filenames until we stop.

    Tanks Pando
    Gert

  6. #6
    Join Date
    Jul 2000
    Posts
    53
    Hi Pando,

    What is the backup controlfile option required for?

    Does this imply that you have a backup of the control file (binary) before the disaster?

    Regards,
    Steve

  7. #7
    Join Date
    Jun 2000
    Location
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    No you dont need any control file at all, although it is recomendable to have one (binary or sql like). If you dont have any you could recreate the controlfile and treat it as a backup controlfile.

    With recover using backup controlfile Oracle doesnt know which SCN to stop and will only stop until we say so. With recover database command Oracle does know where and when to stop.

    The conclusion is as long as we have a backup of datafiles and all archive logs we can recover the database until last archive log. And if we have the online redo logs we can recover until point of failure. Well this is my conclusion :)

  8. #8
    Join Date
    Nov 2000
    Posts
    245
    pando,

    this part I lost. when you recover use backup controlfile,
    you feed arch.log file one by one until the last archive log
    you enter CANCEL to stop the recovery.
    then how you "feed" the online redo log? which command
    you should use? (if I have online redo log)

    Jim

  9. #9
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,448
    hi if you have online redolog you give the redo log name after latest archive log Oracle will treat it as archive logs.
    I cant rememebr exactly but I think recover database using backup controlfile with online redo logs will recover until point of failure, I did this about 2 months ago ... :)

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