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Thread: Chances of corruption

  1. #1
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    Question Chances of corruption

    what are the chances of database getting corrupted when multiple Oracle db's brought down by power(not a procedural db or server shutdown) outage running on Sun sparc server?

  2. #2
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    Define corruption. You will probably be able to recover the database with what is in the online redo logs, if not you can recover with the archive logs. Did the databases start on boot?

  3. #3
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    Just start them up and find out
    Oracle is pretty good doing crash recovery.
    You can ask your storage team or sysadmins about storage status.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

  4. #4
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    The power off itself would hardly corrupt the database. If there is some chance that to corrupt your storrage at hardware level or at OS level, then of course the database will become corrupt as well, but puerly the database will not suffer from that

  5. #5
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    We've encountered this in the past - as all the others have said, Oracle is robust enough to handle itself. The problem you may have is if the O/S or the 'hard' copies of the datafiles get corrupted. If this happens then you need to dig out your backups.

    Funny how a small thing like a power cut can persuade management to buy UPSs when trying to reason with them had failed

  6. #6
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    My home PC has 2 hrs of battery backup.

  7. #7
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    Oracle transactions are ACID (unless you intentionally disable)

    A - Atomic
    C - Consistent
    I - Isolation
    D - Durable

    Durable, once a transaction commits it is persistent even in the event of a system failure.

    The Online redo logs guarantee the recoverability of the Instance.

  8. #8
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    As PAVB said....just crank up the engine...oracle would tell you if the gas is enough...
    Life is what is happening today while you were planning tomorrow.

  9. #9
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    Thanks all for your views

    We had to power down six times this month and a few went with out gracious shutdown. Nothing serious has happened either to hardware as well with software. Most of the hardwares are new and built last year.

    My client has around 100 blade servers and swithces, routers and a/c. To power them we need a generator and client has taken this as top priority now. UPS is not a longterm solution as we do have one and that supports just 15mins. This is not sufficient to bring all the servers down, you all know!

  10. #10
    If everything Oracle wrote to disk actually made it to disk, you are fine. If the storage system said 'yes the redo logs are written to the platter' but in fact did not get them there, then you need to restore something from backup and attempt to roll forward to the last good state.

    Properly scripted, it should be possible to shut down your environment within 15 minutes. You'd need a prepared script triggered directly by the UPS of course (no waiting for a user to type passwords and such) and the shutdown would definitely not be graceful. You'd want to abort the databases, perform an immediate server shutdown, and then shut down the storage system (if separate) towards the end of the 15 minutes. Doing that would minimize the chances of a problem due to power outages.
    Last edited by jhmartin; 04-27-2007 at 12:27 PM.

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