RE: Solaris 10 shmmax

I would also like to understand this a little better. One of my friends is running 10.2.0.2 on Solaris9 and Sun 6900. His shmmax is set to 20G and has 64GB RAM on the server and this is the only instance running on that box. He is seeing multiple shared memory segments on the server. Oracle told him to disable _enable_NUMA_optimization parameter which is enabled by default.
On the other hand, I have a lab server( Sun v490) running 10.2.0.2 on Solaris9. The shmmax is set to 20GB. My SGA is 12GB and I am seeing only one segment from ipcs. I have not tinkered with the NUMA optimization parameter. Per Metalink note 39926.1, multiple shared memory segments in 10gR2 are there for performance reason. Why is the behaviors of shared memory segments in 10gR2 is different on the same platform (v490 versus 6900)?  

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Kevin Closson Sent: Monday, March 26, 2007 12:14 PM
To: ax.mount_at_gmail.com; oracle-l_at_freelists.org Subject: RE: Solaris 10 shmmax          

        I installed Oracle 10.2.0.2 on a Sun Solaris Box 2 weeks ago and I noticed last Monday by running ipcs -a that the shared memory segment arent using the value I have configured, 4GB.                    

        ...what model of Sun server is this? E25K? If so, there are NUMA optimizations in that port and you will get separate shared memory segments for the buffer pool one on each board ("node").                    

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