Summary : oracle rac and ssm-threshold
From: Browett, Darren (dbrowett_at_coquitlam.ca)
Date: 09/23/03
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Date: Tue, 23 Sep 2003 14:15:32 -0700 To: Tru64-Unix-Managers <tru64-unix-managers@ornl.gov>
Thank you to Martin Rønde Andersen [mra@unixera.dk] and Sjolshagen, Thomas (Tru64 UNIX Eng.) [Thomas.Sjolshagen@hp.com]
for their responses.
In summary, ssm_threshold should be left as the default value (8Mb) for the DS series of systems,
not set to zero as stated in the Oracle documentation.
Setting ssm_threshold has more to do with the GS/ES series (NUMA) systems.
If you plan on using gh_chunks (which I am researching into) then ssm_threshold should
be zero regardless of the platform.
I confirmed this with Oracle.
Thanks again
Darren
-----Original Message-----
I am researching what appears to be a performance issue, but I am not
sure if it is
tru64 related or oracle related.
I have two environments,
1. A DS10 with 1Gb of memory running 5.1b connected to a HSG80/BA370
SAN, with oracle 8.1.7
2. A DS20E Dual cpu/500Mhz with 4 Gb of memory, clustered with a DS10 (
that's probably bad)
running V5.1b and having Oracle 8.1.7 and 9.2.0.2 RAC connect to a
HSG80/MA3000. The DS20E is hosting
the cluster file systems.
In environment 1, we can run a query and it takes 1-2 secs to return the
result.
On the clustered system the same query can take upto 20 secs, and this
is on a 8.1.7 version and a 9.2.0.2 version of the database
My first instinct would be that the clustered system is "not" production
and therefore the various buffer caches are not loaded
and therefore the query has to go to disk as opposed to memory.
One thing I did find different between the environments, is the
ssm-threshold variable.
I am not sure if this will have any impact on the cluster. According to
oracle this value should be set to zero for 9.2.0.2 RAC/Tru64 setups.
It is set to the default value on the Standalone System.
Could this variable (ssm-threshold) have an impact on my performance ?
Thank You
Darren
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