>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.
i guess if you want the hot backup to include changes made to the db during
the period of the hot backup then you would need to log switch after...
--
Regards,
Daniel.
"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 Mon Mar 25 2002 - 16:55:34 CST
