Re: 11gR2 smart flash cache
- From: "Zhu,Chao" <zhuchao@xxxxxxxxx>
- To: Jeremy Schneider <jeremy.schneider@xxxxxxxxxxxxxx>
- Date: Thu, 13 Jan 2011 08:59:34 +0800
Nobody using that second tier smart cache yet? We were thinking about doing
a POC on that see how it works; hopefully reduce the load on SAN so SAN can
support more IOPS for more database (by reduce the very IO intensive
database's IOPS);
We plan to install a 300gb fusion IO card onto the host, and let it serve as
the cache;
On Thu, Jan 13, 2011 at 6:35 AM, Jeremy Schneider <
jeremy.schneider@xxxxxxxxxxxxxx> wrote:
> One quick note on this... direct reads do not always indicate temp (or
> even parallel). In 11g Oracle will sometimes start using direct path
> reads for serial full tablescans.
>
> I recently observed this happening a lot with one of my clients. FYI, I
> believe that this particular database had an underconfigured SGA...
> might be related. Interestingly, because Oracle was doing so many FTS
> with direct path, the BCHR looked deceptively healthy.
>
> -Jeremy
>
>
> Steve Harville wrote:
> > I have not tried this setting but I do have some experience with
> > Oracle on flash drives.
> > We are an EMC shop so most I/O is already cached (all writes and all
> > sequential reads). The system cannot cache random reads so that is
> > where I use flash drives. The temp tablespace can benefit the most
> > from flash drives since it exhibits this read pattern. If "direct
> > reads" are a large part of your total wait time then you can probably
> > benefit from moving temp to flash.
> >
> > Steve Harville
> >
> > http://www.linkedin.com/in/steveharville
> >
> >
> >
> > On Wed, Jan 12, 2011 at 5:24 AM, Zhu,Chao <zhuchao@xxxxxxxxx> wrote:
> >
> >> hi, List friends,
> >> Oracle has been promoting this flash cache as second tier cache for
> >> oracle for a while; Just wondering whether anyone has used this within
> the
> >> industry?
> >> We typically have 30gb-60gb SGA supporting 1TB-4TB database; We found
> >> usually 30gb or 60gb cache size does not really matter much for majority
> of
> >> our database(some has big diff though, depends on workload
> profile/active
> >> dataset); But a 300gb flashdisk might make huge difference, and help
> reduce
> >> the IOPS load on the SAN side?
> >>
> >> Looking forward to industry experience;
> >>
> >> Thx
> >>
> >>
> >>
> >> --
> >> Regards
> >> Zhu Chao
> >>
>
> --
> http://www.ardentperf.com
> +1 312-725-9249
>
> Jeremy Schneider
> Chicago
>
>
--
Regards
Zhu Chao
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