Re: AW: Re: AW: Re: amm vs. asmm

Hi

I have also observed behaviour stated in https://twitter.com/jolliffe/status/1094195271448186881?s=20 <https://twitter.com/jolliffe/status/1094195271448186881?s=20.>

I have seen it when no minimum memory parameters are set. For example I have a customer who has a database with 40GB sga_target set, no other memory parameters and after 3 or 4 weeks the buffer cache was left with 64MB only.

So I think the best practice would be setting minimum and sga_target.

BR

On Fri, Jan 24, 2020 at 10:48 AM Stefan Koehler <contact_at_soocs.de> wrote:

> Hello Ahmed,
> there are also problems with ASMM, e.g.
> https://twitter.com/jolliffe/status/1094195271448186881?s=20.
>
> There is no better way than doing malloc() or mmap() on your own - just
> kidding ;-)
>
> I see no reason to change Oracle's memory management if nobody currently
> faces any issue. However in general I personally favor ASMM (or completely
> manual SHM management) from the start but why changing something that does
> work right now in your case. By the way even some guys from Oracle do not
> favor AMM in first place, e.g.
> https://twitter.com/MikeDietrichDE/status/666564901536727040?s=20 or
> https://mikedietrichde.com/2016/03/04/parameter-recommendations-for-oracle-database-12c-part-i/
>
>
> P.S.: Moving Oracle away from AIX is almost always a good idea (not just
> in case of current problems). IMHO there is only one good reason (real need
> for best single thread CPU performance) to stay on Power / AIX - but then
> you need to configure SMT carefully and benchmark it as well.
>
> Best Regards
> Stefan Koehler
>
> Independent Oracle performance consultant and researcher
> Website: http://www.soocs.de
> Twitter: _at_OracleSK
>
> > "ahmed.fikri_at_t-online.de" <ahmed.fikri_at_t-online.de> hat am 24. Januar
> 2020 um 10:11 geschrieben:
> >
> > hello Steffen,
> >
> > it is just an observation that we have made in the past. After we heard
> that there are problems with AMM (I guess from you too in DOAG :-) ). I did
> few performance tests and have very negative impact of AMM on our
> application. In addition to that I doubt that the DBA has a factual reason
> to use AMM. It was may be only coincidence. Furthermore I'm worried that
> someone will look elsewhere for current performance problems. For example,
> to believe that the solution is to use a different OS ;-)
> >
> > Grüße
> > Ahmed
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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