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Re: Online vs offline backups

From: Jeremiah Wilton <jwilton_at_speakeasy.net>
Date: Wed, 19 Jun 2002 12:50:25 -0800
Message-ID: <F001.00481E18.20020619125025@fatcity.com>


The reason this won't work is because you open DEST and generate new SCNs and log entries before you get a chance to set all tablespaces to read-only. So you can't then shut that database down and apply log entries from a different database. By opening DEST, you cause it to diverge from the redo stream of MYDB. There is then no way to make DEST take the logs of MYDB. Also, you can't set SYSTEM to read-only, so the whole thing can't even work in theory.

--
Jeremiah Wilton
http://www.speakeasy.net/~jwilton

On Wed, 19 Jun 2002, Charlie Mengler wrote:


> Why won't the following work?
>
> I take a hotbackup of a instance (MYDB) from a system called SRC
> by using a collection of "rcp" commands to copy the datafiles
> onto another system called DEST.
>
> I wave my magic wand across DEST & bring up a copy of the orginal
> instance (MYDB) on DEST and set all tablespaces to READ ONLY
> except SYS, RBS & TEMP. I allow users into the instance for a
> while & then shutdown the database; all the while I'm collecting
> redo logfiles from MYDB on SRC. I STARTUP RESTRICT the MYDB on DEST,
> ALTER the tablespaces back to READ WRITE mode, and SHUTDOWN IMMEDIATE.
>
> Next I move all copies of the controlfiles on DEST out of the way &
> STARTUP NOMOUNT
> CREATE CONTROLFILE REUSE DATABASE "MYDB" RESETLOGS ARCHIVELOG
> ...
>
> and apply the redo logfiles from SRC.
>
>
> ALTER DATABASE OPEN RESETLOGS;
>
> Next I set all tablespaces to READ ONLY
> except SYS, RBS & TEMP. I allow users into the instance for a
> while & then shutdown the database; all the while I'm collecting
> redo logfiles from MYDB on SRC. I STARTUP RESTRICT the MYDB on DEST,
> ALTER the tablespaces back to READ WRITE mode, and SHUTDOWN IMMEDIATE.
>
>
> Next I move all copies of the controlfiles on DEST out of the way &
> STARTUP NOMOUNT
> CREATE CONTROLFILE REUSE DATABASE "MYDB" RESETLOGS ARCHIVELOG
> ...
>
> and apply the redo logfiles from SRC.
>
>
> ALTER DATABASE OPEN RESETLOGS;
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Jeremiah Wilton INET: jwilton_at_speakeasy.net Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
Received on Wed Jun 19 2002 - 15:50:25 CDT

Original text of this message

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