Re: Database backups

firstly i knew some smart arse would write such a reply,,,, my reply was trying to be generic!!!!!!

a cold backup is a consistent backup of a database that has shutdown normal (minus online redo logs) thus negating the need to roll forward from such a backup. yes in an archivelog db you could bring back a df from a cold backup set and roll forward but my point was u would not normally roll forward from a complete consistent cold backup even though you could do....

regarding log switch the user states it is an ebusiness environment (oltp!) so we are probably putting tx's through it. well as we both know worst case scenario is u lose your current online redo log, thus tx's that may have not checkpointed (yes i know we can alter the frequency of the checkpoint) so online redo sized to switch every 15 mins means worst case scenario is we lose 15 mins of bussiness data....

so before we enter into a "my dad's bigger than your dad" argument there are 15 billion approches to oracle backups so don't call it "dreadfull advice", it's just another way of looking at it.

reagrds,

daniel...

"Howard J. Rogers" <dba_at_hjrdba.com> wrote in message news:a7el2i$hek$1_at_lust.ihug.co.nz...
> Comments below
> HJR
> --
> ----------------------------------------------
> Resources for Oracle: http://www.hjrdba.com
> ===============================
>
>
> "daniel" <test_at_test.com> wrote in message
> news:a7deuk$417$1_at_newsg2.svr.pol.co.uk...
> > as a rule of thumb u don't roll forward from a cold backup, (yes, yes I
> know
> > you can but lets not get into bad habits)....
> >
>
> That's simply not true, and it's not a bad habit either. Of course you
can
> roll forward from a cold backup. And taking cold backups is much easier
> than the hot variety.
>
> > you can use just hot backups no probs and can recover quicker from them
> >
> > pointers;
> >
> > have multiple ctl files spanning physical disks
> > multiplex your online redo logs across physical disks
> > aim to log switch every 15 mins
>
> Dreadful advice. If you want performance, log switch every 24 hours, in
the
> dead of night, when no-one gives a damn about the huge amount of I/O the
> associated checkpoint will induce. If you want Instance Recovery in ten
> seconds, log switch every second or so. Somewhere in between those two
> extremes will be a happy medium for *you*.
>
> > every time you change the db structure "alter database backup
controlfile
> to
> > trace"
>
> Equally dodgy advice, I think. Backup to trace should be routine. Every
> backup should include it.
>
> > after the hot backup take a copy of the ctlfile and "archive log
current"
> > and make sure your archive redo logs are protected stream them off
> somewhere
> > else every 15 mins
>
> Depends on your log switch rate, of course (see above!!)
>
> > also when you take the hot backup keep a copy locally if enough space
also
> > stream to tape and if recovery time is an issue copy to some network
> storage
> >
>
> Agreed. Keep as much on disk as possible.
>
> Regards
> HJR
>
> > good luck
> >
> > daniel...
> >
> >
> > "Dale DeRemer" <dderemer_at_agmc.org> wrote in message
> > news:a7dcs8$q7u$1_at_malgudi.oar.net...
> > We are new the the Oracle world. We want our ebusiness server to be
7x24.
> > Never, ever down. Meaning... no cold backups. So, our question is this:
If
> > we use hot backups, (RMAN), and never take a cold backup, will we be
able
> to
> > recover from any failure. Additionally, what is the impact, or
difference
> in
> > recovery time for a system with no cold backups, vs. one with a cold
> backup
> > done once a week, or once a month?The DB is 75GB and will grow to about
> > 100GB over the next year. It will be updated in batches from our
> mainframe.
> > Users will not update it. Thanks for your help.
> >
> >
> >
> >
>
>
Received on Fri Mar 22 2002 - 14:39:05 CST