Re: DB_BLOCK_BUFFERS --> DB_CACHE_SIZE

"Richard Foote" <richard.foote_at_bigpond.com> wrote in message news:NM1Zb.66762$Wa.64784_at_news-server.bigpond.net.au...
>
> "Howard J. Rogers" <hjr_at_dizwell.com> wrote in message
> news:40342623$0$15135$afc38c87_at_news.optusnet.com.au...
> >
> > "Charles Davis" <cdavis10717_at_comcast.net> wrote in message
> > news:87-dnd-4qp3muandRVn-gg_at_comcast.com...
> >
> > Just be warned: if you use the multiple buffer pools feature available
> since
> > 8.0, then it works completely differently in 9i compared to 8.0 and 8i.
In
> > 8.0 and 8i, you allocated a total buffer cache (block_buffers x
> block_size),
> > and then carved bits off that total to give you your other two pools. So
> > with block_buffers set to 20000 (ie, 160M), and buffer_pool_keep set to
> 4000
> > (32M) and buffer_pool_recycle set to 6000 (48M), your total buffer cache
> > was.... 160M. The two pools come *out* of the total allocated with
> > block_buffers.
> >
> > In 9i, by contrast, db_cache_size only sets the size of the default
pool.
> If
> > you then set db_keep_cache_size and db_recycle_cache_size, those extra
> > caches are actually added on: your total buffer cache size becomes the
sum
> > of all three parameters.
> >
>
> Hi Howard,
>
> Just wait a God-damned minute !!
>
> In his tuning book and in various articles, your mate Don Burleson ;)
states
> that if you have a db_cache_size = 3G, a db_keep_cache_size=1G and a
> db_recycle_cache_size = 500M, then the "Default" pool is 1.5G in size. He
> states that the Default Pool size = db_cache_size - db_keep_cache_size -
> db_recycle_cache_size.
>
> Now DB as we know is one of the worlds leading Oracle "experts", surely he
> can't have this elementary tuning concept incorrect, can he ? I mean, he's
> only recently published an e-book (at DBAzine) stating exactly what I said
> above, how can someone tune a database when they don't know how to
calculate
> the size of the Default Pool ???
>
> Yes, I did tell him of this mistake sometime ago and yes he never
> acknowledged my correction ...
>
> Cheers
>
> Richard

I was going to say "you can't be serious". But I have that sinking feeling that you can. This is 101 stuff, surely!

Regards
HJR

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