Re: Standby recovery

We have 126 datafiles in a database;
it seems that oracle attempts to start 126*2 processes... from alert log:

attempting to start a parallel recovery with 252 processes parallel recovery start successful, got 8 processes

Should we really allow for 252 recovery processes, or it is nonsense regarding 8-cpu machine?

Thanks!

"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:3f5487a7$0$6524$afc38c87_at_news.optusnet.com.au...
> You're throttled by the fact that parallelization of log apply is only
done
> on the write. There's still only one managed recovery process *reading*
the
> redo, and that isn't alterable, from memory.
>
> So if you've already parallelized the recovery process, that's about as
far
> as you can take it.
>
> On the other hand, if you've got 8 CPUs, then I'd suggest you increase the
> degree of parallelization to (maybe) 16, though it really rather depends
on
> the number and layout of the data files as to whether that will help at
all.
> But I'd certainly give it a go. Usual advice, as far as I remember it, is
> two or three recovery processes per datafile.
>
> Regards
> HJR
>
>
> "Goran D." <goran99_makni_at_yahoo.com> wrote in message
> news:bj20ac$db2$1_at_fegnews.vip.hr...
> >
> > Hello,
> >
> > This is actually a general question, although it regards to a specific
> > database.
> > We have a physical standby database for a production database
(8.1.7.4.0)
> at
> > another location; the managed recovery and automatic archiving take
place
> > without problems.
> > However, we noticed that recovery of a single arch.log is rather slow -
> the
> > machines (8 CPU HP-UX) and storage boxes (EMCs) are the same.
> > During periods of peak activity , the production database takes about a
> > minute to generate a single redolog of 1GB; after it is transferred to
> > standby machine, standby database needs (average) 3-5 minutes to apply
> this
> > particular log.
> >
> > We tried to establish parallel managed recovery (8 processes), but
gained
> > improvement of only 10-20%.
> >
> > This still represents no serious problem, as the time during the day is
> > still sufficient to apply all the logs. However, if activity of the
> > production database increases, we fear that standby would not be capable
> of
> > performing the recovery - ie that the production would generate more
logs
> > during the day that the standby is capable of applying.
> >
> > I have to emphasize that this is not the matter of network transport
> (which
> > is satisfactory), rather the speed of applying logs during recovery.
> >
> > So is there a way to speed-up the recovery process..? Any suggestions
> > welcome.
> >
> > Regards,
> > Goran Dokmanovic
> > Oracle DBA
> > VIPNet d.o.o
> >
> >
>
>
Received on Tue Sep 02 2003 - 07:45:11 CDT