Re: Metrics for Swingbench benchmarks

On Fri, Mar 14, 2008 at 10:44 AM, John Hallas <john.hallas@xxxxxxxxxx>
wrote:

>  The main misunderstanding I have is the difference between 95% and 90%.
> The 2nd node is available but not in use. I know there will be heartbeat
> and other maintenance work going on and I am also aware that the cache
> fusion will keep the 2 SGAs in sync, however I have been searching for more
> information on what is happening in the preffered/available modes and any
> thoughts appreciated.
>
When you say "preferred/available" are you referring to the "Service" you
created?  If so then the only effect of this is that all connections are
going to the preferred node - however the other node is up and running and
fully part of the cluster.

One thing that comes to mind right away - even though your second node is
"not in use" it still maintains a complete mirror of the GRD (global
resource directory - things like cluster-wide locks).  Also, there's a good
amount of additional messaging related to SCN generation.  Just some shots
in the dark, but I wonder if you could statically force all lock masters to
the preferred node and decrease SCN traffic by tweaking something like the
MAX_COMMIT_PROPOGATION_DELAY init param?  That might get you some of those
percents back...

**
PS - I'm loving this whole thread because it's a perfect example of the
bogus hype around RAC.  Clustering is powerful technology and honestly, a
lot of applications will scale well with no modifications on RAC.  (The
well-designed ones.)  But clustering is complicated and if a sales person
gives the impression that you can just run any application on RAC to make it
magically faster -- baloney!!!!


-- 
Jeremy Schneider
Chicago, IL
http://www.ardentperf.com/category/technical

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