Re: backup question

From: Howard J. Rogers <howardjr_at_www.com>
Date: Mon, 29 Jan 2001 23:20:12 +1100
Message-ID: <3a755fc6$1_at_news.iprimus.com.au>


Hi Cristian,

Backup and Recovery is a *huge* topic.

Are you in archivelog mode?

You are taking dumpfile exports... that's a logical backup. You are copying datafiles/redo logs/control files -that's a physical backup. When things go wrong, sometimes, you restore from the logical backup, sometimes from the physical. It all depends on what's gone wrong. Frequently, you restore from logical backups when Users do daft things. And you restore from physical backups when hardware fails, or when data files are mistakenly deleted, or discovered to be corrupt.

If you are doing restores of the physical backup, *what* you restore depends entirely on whether you are in archivelog mode or not. If you are, you restore the *one* file that's causing the problem (or as many as are causing problems), and then apply archives. If you are NOT, then you restore the entire complement of files, and take the entire database back to the way it was at the time of doing the backup.

What you generally cannot do (or, rather, shouldn't do) is combine a physical restore with a logical one, because running import after restoring a datafile is either a complete waste of time, or results in a right old mess of duplicated records and the like.

As to whether you have to shut the database down before doing the backup: it all depends.

I don't mean to be funny here, but until you understand the *principles* of backup and recovery, you are likely going to stuff up big time. Try downloading the 70-page document at
http://www.geocities.com/hjroz2000/backup_and_recovery.htm and see how you go. Ignore the RMAN chapters -that's only relevant when you have version 8 or above (but it's about time you upgraded). I'll happily take your questions via e-mail after that.

Regards
HJR Cristian Veronesi <c.veronesi_at_crpa.it> wrote in message news:3A7548E9.7D69FEE3_at_crpa.it...
Every night I run a task that exports my oracle database on a DMP file first and then saves every single file stored on the the server (SCO Openserver 5.0.4 + Oracle RDBMS 7.3.4) on a tape. I am wondering whether, after a system crash, restoring all the Oracle files (data files, control files, etc.) would be enough for having Oracle up and running again or have I to reinstall Oracle and then import all the DMP files?
If I'd shut down the database before to save the files something would change?

Sorry for my ingenuousness :)
Best regards, Cristian

--
Cristian Veronesi ><((((ยบ> http://www.crpa.it

If Bill Gates had a dime for every time a Windows box crashed...
Oh, wait a minute... he _already_ does! ;)
Received on Mon Jan 29 2001 - 13:20:12 CET

Original text of this message