Re: large memory allocation

You can run 64 bit Oracle, so the 32 bit limit can be exceeded.

You can overcome the LRU algorithm with things like pinning and setting other db parameters. DB block buffers being one of things where you can the biggest gains. You can also do things like set the cache option for tables that will be read frequently.

Every application will have different performance characteristics which is why tuning is an empirical and not a completely rule based process.

Chances are you will become I/O and CPU bound long before RAM become an issue with a machine with 30GB of Ram.

Chris

"Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote in message news:tess7nq1476fb6_at_beta-news.demon.nl...
>
> <213.74.48.226 [hopehope_123_at_yahoo.com]> wrote in message
> news:4UtH6.144086$47.2082010_at_news.bc.tac.net...
> >
> > Dear Oracle community,
> >
> > Sorry this is a newbie question.
> > Is it possible to allocate large memory with oracle such as 30gb. and
> > if it is possible how can affect the performance?
> > Can i use that much memory as data caching?
> >
> > Kind Regards,
> >
> >
> >
> > ==================================
> > Poster's IP address: 213.74.48.226
> > Posted via http://nodevice.com
> > Linux Programmer's Site
>
> What were you planning? Running an in-memory database? That won't work due
> to Oracle's lru algorithms. Running untuned applications only?
> The guideline of Oracle (and my experience too) is that the SGA shouldn't
> exceed 1/3 of physical RAM. Otherwise excessive paging by the O/S will be
> the result.
> Also, there would be a theoretical limit 2^32 -1 on 32-bit platforms, but
 I
> believe I have read the maximum is 4G.
> And, I can't see why on earth you would need 3 G cache, other than for the
> reasons above. It won't help you a bit, and it would hurt performance.
>
> Regards,
>
> Sybrand Bakker, Oracle DBA
>
>
>
Received on Tue May 01 2001 - 17:18:13 CDT