Nicolas Williams writes:
> On Wed, Oct 03, 2007 at 04:31:01PM +0200, Roch - PAE wrote:
> > > It does, which leads to the core problem. Why do we have to store the
> > > exact same data twice in memory (i.e., once in the ARC, and once in
> > > the shared memory segment that Oracle uses)?
> >
> > We do not retain 2 copies of the same data.
> >
> > If the DB cache is made large enough to consume most of memory,
> > the ZFS copy will quickly be evicted to stage other I/Os on
> > their way to the DB cache.
> >
> > What problem does that pose ?
>
> Other things deserving of staying in the cache get pushed out by things
> that don't deserve being in the cache. Thus systemic memory pressure
> (e.g., more on-demand paging of text).
>
> Nico
> --
I agree. That's why I submitted both of these.
6429855 Need way to tell ZFS that caching is a lost cause
6488341 ZFS should avoiding growing the ARC into trouble
-r
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