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RE: Oracle backup questions...

From: Jack van Zanen <>
Date: Wed, 19 Sep 2007 06:39:55 +1000
Message-ID: <00ae01c7fa34$152d9260$3f88b720$@com>

Of the top of my head

  1. Archives are written once the redo log switches in one go
  2. If you lose your controlfiles and restore an old one this has no record of "future" archives. To be able to apply these you need to recover using backup controlfile.
  3. dunno of the top of my head
  4. delete obsolete deletes the backups that are still available but out of retention policy I believe, expired deletes the ones that are removed from the media
  5. backup database plus archivelog.


-----Original Message-----
From: [] On Behalf Of Mason Loring Bliss
Sent: Wednesday, 19 September 2007 5:04 AM To:
Subject: Oracle backup questions...

I'm working on Oracle back-up and recovery, and I've run across a few random questions from looking at what other folks do, and from experimenting on my own.

  1. What is the on-disk state of archive logs at arbitrary times? Does Oracle only write them out when they are complete and usable, or does it slowly fill them in over time? Recovering the final archive log here seems to consistently fail, until the next archive log is in place, at which time the one that was previously last is imported without issue.
  2. Is there any meaningful difference between "recover database" and
    database using backup controlfile"?
  3. What is "crosscheck archivelog all" as opposed to "crosscheck backup"?
  4. How does "delete obsolete" differ from "delete expired backup"?
  5. How do we control the frequency of archive log generation? Do I simply say
    "alter system switch logfile" and wait a bit, or does that only affect redo
    logs? Should I "alter system archive log all" instead? In short, what should I do to try to bring the archive logs as close to current as is possible?

Thanks very much for your help!

Mason Loring Bliss        Oderint dum metuant!     awake ? sleep : random() & 2 ? dream : sleep;

Received on Tue Sep 18 2007 - 15:39:55 CDT

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