Backing up Online Redo Logs
happy...@my-deja.com
Hi I'm just about to test my hotbackup of a 7344 instance, I've
put copies of my datafiles (produced whilst in backup mode), my
archive-logs and control-files onto a clean machine, but is it
feasible to just put copies of my online redo-logs over, common
sense indicates that they're being continually updated and so doing
a Unix copy of them will probably produce an inconsistent image, yet
I can find no documentation on how to backup an online-redo log.
So on a clean machine is the only thing I can do is a point-in-time
recovery with a reset logs option ??
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Before you buy.
Thomas Kyte
(if that email address didn't require changing)
On Wed, 20 Oct 1999 07:33:09 GMT, you wrote:
>
>
>Hi I'm just about to test my hotbackup of a 7344 instance, I've
>put copies of my datafiles (produced whilst in backup mode), my
>archive-logs and control-files onto a clean machine, but is it
>feasible to just put copies of my online redo-logs over, common
>sense indicates that they're being continually updated and so doing
>a Unix copy of them will probably produce an inconsistent image, yet
>I can find no documentation on how to backup an online-redo log.
>
you never backup an online redo log -- thats why the documentation on how to is
'lacking'.
From the backup section in the admin guide:
--------------------------------------------------------
• If you want a copy of the current online log, then archive it.
Archiving means the online log will no longer be the current log.
If you end up copying a current online log, the copy will appear
as the end of the redo thread. However, additional redo may have
been generated in the thread. If you ever attempt to execute
recovery supplying the redo log copy, recovery will erroneously
detect the end of the redo thread and prematurely terminate,
possibly corrupting the database.
--------------------------------------------------------
so, after you've done the hot backup -- archive the current online redo log and
then backup the archived redo log.
>So on a clean machine is the only thing I can do is a point-in-time
>recovery with a reset logs option ??
if you do not have the online redo logs from the other instance -- it'll be more
like a recover until cancel with an open reset.
Typically you will have your online redo logs duplexed or triplexed -- reducing
the probability of data loss in a catastrophic failure. It is expected that
some copy of the online redo logs may survive. If all copies of the online redo
logs are missing during media recovery -- you will only be able to recover as
far as the archives go.
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.
--
See http://osi.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'...
Current article is "Part I of V, Autonomous Transactions" updated June 21'st
Thomas Kyte tk...@us.oracle.com
Oracle Service Industries Reston, VA USA
Opinions are mine and do not necessarily reflect those of Oracle Corporation