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  1. #1
    Join Date
    Dec 2003
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    1,074

    Unanswered: Backup controlfile before/after tablespace created

    I was reading in the Oracle documentation that a backup of only the control file is good practice before & after a tablespace is added, but only if you're operating in ArchiveLog mode.

    Conceptually, I get the point, but how does that help during the actual recovery? If you want to restore the database to the state prior to the tablespace update, do you specify the pre-tablespace controlfile by name?

    -Chuck

  2. #2
    Join Date
    Jun 2004
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    796
    Provided Answers: 1
    The name & location of the control file/s is specified in the init.ora file; you can change the details in this file if you want to, but what the documentation is suggesting is that you make your backup copies of the control files & save them to another location, then if you need to use them you physically place whichever one you need to use in the same location as the existing one (effectively overwriting it), so that when you start up the Db the init.ora file will pick it up.
    90% of users' problems can be resolved by punching them - the other 10% by switching off their PCs.

  3. #3
    Join Date
    Dec 2003
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    1,074
    Thanks, that makes sense.

    (I ordered the RMAN 9i Recovery Manual last Monday, and it's on backorder at Amazon. That's why I'm asking questions on this topic again. I think these will be answered when I get the manual, but if you'd help with some hints until then, I'd appreciate it.)

    Another comment that I came across that I don't fully understand how it's implemented dealt with backing up high-use tablespaces on a more frequent schedule (backed up nightly) than the rest of the tablespaces in the database (full backup Sundays). This should make your recovery times faster. Does RMAN "know" that a particular tablespace backup is more recent than the full backup, and is it smart enough to use it during instance recovery?

    We're trying to determine our backup strategy, and how it applies to the pre- and post-production state of the database, preparing for the case when we need to return only a portion of the database to a pre-production state. I've been suggested to take an export before production, and a full database backup after. It also sounds like enabling Flashback and a post-production backup is another solution. We could also try out RMAN's TPITR with a post-production backup. Would backing up a the tablespaces affected by production be another approach? Would it speed up TPITR?

    Thanks again for your help,
    Chuck

  4. #4
    Join Date
    Jun 2004
    Posts
    796
    Provided Answers: 1
    This is probably referring to the fact that RMAN can recover a specific tablespace, as well as the whole database (It's sometimes referred to as a subset of the database); obviously recovering a tablespace will be a lot faster than recovering a complete database.

    Flashback is not meant to be a recovery tool, as such; it's designed to allow you to see what a tablespace looked like at a particular point in the past - however, there's nothing to stop you from then copying the data to another table, turning flashback off & then playing with the data that you 'recovered'.

    TPITR is effectively the same as Flashback EXCEPT Flashback will give you only a 'view' of the tablespace - if you want to save the data you have to copy it to another table, whereas TIPTR will set the tablespace to how you want it without the need to copy data.

    Hope this helps.
    90% of users' problems can be resolved by punching them - the other 10% by switching off their PCs.

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