Re: quick hot backup question...

Howard,

A Question on The same lines...

Is it really mandatory that you do Alter system Archive Log Current or Alter System Switch Logfile after the End Backup Command or after the entire script is done ?

Yeah i know that u need to take a Backup of the Log that Has the Alter Tablespace End Backup command. I am doing that now in all my backup scripts but my feelings is that it is not mandatory that it be done. Am i right ???

I Feel that if u dont have the End Backup Command archived and all your redo and archives after the Backup got thrashed you can say <<Alter database Datafile <filename> end backup>>. So it does not make any difference you have the logs or not. Anyways u have lost your data and u just need to move the datafile back out of the backup mode and anyways you will be saying open resetlogs.

Am i right in this assumption.

Your comments on this are valuable.

Thanks.

Best Regards,
Ganesh R

"Glen A Stromquist" <gstromquist_at_nospamyahoo.com> wrote in message news:<FpNn8.17155$mR1.434250_at_news2.telusplanet.net>...
> Thanks Howard
>
> The reason for all this was I am just brushing up for an exam (finally) and
> the oracle tutorial I was running through said that a logfile switch and
> forced checkpoint should be done before a hot backup. I was pretty sure the
> checkpoint was done when the file was put in backup mode, but you confirmed
> it.
>
> I've had this discussion with you before regarding doing a log switch after
> the datafiles are copied then copying the archive log generated during the
> backup, and in the past went to great pains writing my script to do just
> that. However after I "restored" a database to another location (clone) from
> a set of hotbackup files and applied all the archive logs to it, I realized
> that what I was doing was ok, but not really necessary, like you said.
>
> End result is that I don't bother anymore, and writing the dynamic backup
> scripts is a whole lot easier.
>
>
> "Howard J. Rogers" <dba_at_hjrdba.com> wrote in message
> news:a7o4ju$vfn$1_at_lust.ihug.co.nz...
> > If you're doing O/S online backups, then there's no need for a preliminary
> > checkpoint, because that's precisely what the 'begin backup' command
> forces
> > (at least for the datafiles of the tablespace involved).
> >
> > The one about a preliminary log switch (presumably because you are about
> to
> > copy the archives) is always a curious one. Lots of people do it, and
> I've
> > never really understood why. Usually the justification is that without
> it,
> > you are short of the current redo log, so you may lose data. There's
> > something to that, I suppose. But it's also usually (so I find) because
> > people view a backup as an isolated event, whereas the truth of the matter
> > is, of course, that what you don't backup tonight you will backup
> tomorrow.
> > So if there's a bit of current redo left unbacked up, who cares?? You'll
> > get it when tomorrow's backup is performed, and in the meantime there's no
> > possible risk of data loss because you've multiplexed your online redo
> logs,
> > and then mirrored them with hardware RAID. Haven't you?? ;-)
> >
> > The other thing that mystifies me about forcing a log switch in order to
> get
> > an archive of the current log is that it only makes another log the
> current
> > log. So you can *never* really be completely and utterly up-to-date with
> > redo copies, unless you stop all your users doing things: there'll always
> be
> > a new piece of current redo which you haven't backed up today. Hence cold
> > backups, of course.
> >
> > That said, a log switch does no real harm -except induce a
> > performance-hitting checkpoint.
> >
> > Regards
> > HJR
> > --
> > ------------------------------------------
> > Resources for Oracle : www.hjrdba.com
> > ============================
> >
> > "Glen A Stromquist" <gstromquist_at_nospamyahoo.com> wrote in message
> > news:jpMn8.11561$EV.366849_at_news1.telusplanet.net...
> > > In my online backup scripts I don't do a logfile switch or force a
> > > checkpoint before copying the datafiles.
> > >
> > > Is this recommended by Oracle?
> > >
> > > I'm wondering if I overlooked something when writing my scripts, I have
> used
> > > my online backups on occasion to create a clone db, so I know they
> "work"
> > > the way I'm doing it now, but I guess it can't hurt to build in a
> logfile
> > > switch and/or force a checkpoint as part of the script as well.
> > >
> > > Curious to hear what others do regarding this....
> > >
> > >
> > > cheers!
> > >
> > >
> >
> >
Received on Wed Mar 27 2002 - 00:02:12 CST