Re: Cold & Hot backup!

Going back to the original question, I think the poster was saying that if he took a cold backup every month, then he could delete all the archivelogs that he had saved before the cold backup. If he was taking cold backups once in two months, he would have to save the archivelogs for the two months. If my last cold backup was in March, I would need all the archive logs from March to perform complete recovery. If I do a cold backup every week, I dont need to store hundreds of archivelogs from the past 6 months. I think everybody would agree that after a cold backup, you can delete all the archives generated before the database was shut down, since at the point of shutdown, checkpoints make sure that the controlfiles and datafiles are consistent. Mixing hot and cold backups in your backup strategy is actually a good thing and storage needs DO differ depending on the type of backups for the reason I mentioned above.

Thomas Kyte <tkyte_at_us.oracle.com> wrote in message news:<9ik4m202ohv_at_drn.newsguy.com>...
> In article <3b4d5e29_at_news.iprimus.com.au>, "Howard says...
> >
> >
> >"Thomas Kyte" <tkyte_at_us.oracle.com> wrote in message
> >news:9i731s029gc_at_drn.newsguy.com...
> >> In article <3b4661cd_1_at_news1.prserv.net>, <hartono_nugroho_at_attglobal.net
 says...
> >> >
> >> >Thanks for your quick response.
> >> >
> >> >I want to be able to delete all of the old archive redo log files after
 I
> >> >did a cold backup and start over again with the ARCHIVE redo log.
> >> >My undersanding is that by using cold backup, you only need to backup the
> >> >ONLINE redo log file, while in hot backup you need to have all
> >> >the ARCHIVE redo log file. Or do Oracle automatically reuse the archive
> >> >redo log when you issue alter tablespace begin backup command?
> >> >Currently I am using only a cold backup so I don't really know the
 situation
> >> >of hot backup.
> >> >
> >> >Regards,
> >> >Ari
> >> >
> >>
> >> wrong -- you NEVER backup online redo log files in ANY CASE.
> >
> >I would clarify to this extent: if you are performing COLD backups, then
> >backing up the online redo logs is useful, but not essential.
>
> it is not COLD vs HOT when talking about online redo log. Its archivelog vs
> noarchivelog.
>
> I disagree totally if you are in ARCHIVELOG MODE. In that case, backing up
> online redo is only asking for TROUBLE. Backing it up can only make it so that
> it is too easy for you to overwrite your CURRENT online redo logs -- thereby
> making it not possible to fully perform media recovery.
>
> Been there, seen it done. "Hey, had a failure -- its ok, we have backups. Well
> HURRY UP and restore them -- ok. Whoa -- why can't we recover all of our
> transactions? because I just overwrote the current online redo logs that hadn't
> been archived yet with out backups, sorry about that"....
>
> It is *never* necessary, it just *shouldn't* be done as a matter of practice.
>
>
> > The Oracle
> >docs themselves says making such a backup may make recovery procedures
> >easier under certain circumstances.
> >
>
> full cold backups of a database in noarchivelog mode would be the only case.
>
> since production systems by and large must be running in archivelog mode -- the
> applicability of backing up online redo log is very very small.
>
> >But, to the extent that a database once closed has *no* online files of
> >whatever nature, then your statement above is actually 100% correct.
> >
>
> once closed "normally" (not shutdown aborted)
>
> >Regards
> >HJR
> >
> >
> >
Received on Sat Jul 21 2001 - 16:36:42 CDT