Re: 11gR2 DB Flash Cache

FWIW,..I don't see v$file_optimized_histogram populated in 12.2 too

Cheers
-Fairlie

On Wed, Feb 8, 2017 at 8:40 PM, Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk> wrote:

>
> There are some high-level stats in x$kcbwds. If you're running with just a
> default 8K buffer cache then you'll want POOL_ID = 3; any column with L2 in
> its name is flash cache - that will tell you something about reads and
> writes.
>
> For 11.2.0.4 there's also x$kcfiofchist which is the x$ underneath the 12c
> v$file_optimized_histogram view. I don't recall whether it's actually
> populated and whether it could be trusted, though.
>
> Regards
> Jonathan Lewis
>
>
>
>
>
> ________________________________________
> From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> on
> behalf of Jack Applewhite <jack.applewhite_at_austinisd.org>
> Sent: 07 February 2017 20:26:27
> To: oracle-l_at_freelists.org
> Subject: 11gR2 DB Flash Cache
>
> We recently moved our busiest two 11gR2 EE databases (about 1TB each) from
> an X4 ODA to an X5. It was via switchover to physical standbys, so we
> hadn't been using - didn't really know about (no Flash Cache SSDs in X4s) -
> Database Smart Flash Cache. Last weekend we were able to configure each DB
> (one per node on the X5 ODA) to have 192GB Flash Cache (out of 512GB total
> available in the ODA).
>
>
> Well, it's been better than Christmas! We've been marveling at the HUGE
> overall performance improvement we see. The main App hitting one of the DBs
> is a COTS Student Information System, hit by all of our 12,000 or so
> teachers and staff. There were a bunch of Selects in the App's code that
> would drive load averages to 200 - 400% periodically during the day. Now we
> rarely see load averages approaching 100%, usually staying around 25%.
> StatsPac reports show the dramatic differences in waits, as well as the
> SQLs found to be hogs.
>
>
> My question ... Is there a way to get visibility into the flash cache to
> see what's in there? Since this is 11g, the 12c-only V$FlashFileStat view
> is not available and V$Sess_IO only has the session level
> Optimized_Physical_Reads column. None of the SGA-related views that I've
> found have info. about the flash cache. Mr. Google and MOS haven't helped
> either.
>
>
> Any way to see what's going on in the Flash Cache?
>
> Thanks.
>
> --
> Jack C. Applewhite - Database Administrator
> Austin I.S.D. - MIS Department
> 512.414.9250 (wk)
>
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> But ... -- "Oh Well" F.M.
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-- 
Fairlie Rego
Senior Oracle Consultant
http://www.linkedin.com/in/fairlierego
https://fairlierego.wordpress.com/
_at_fairlierego

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