Re: Processes and Semaphores on Solaris 5.9 with Oracle 8.1.7.4

Kevin Lange wrote:

>My question to you all is this: The note in metalink was sketchy on what it
>would do to the system if we raised the SMMNS parameter up on the system.
>Does anyone have any experience in what affects raising the ceiling on
>Semaphores might have to this kind of system ?
>
>
>

Semaphores are implemented through device driver. Increasing the number of semaphores will increase
the memory used by Solaris kernel by 2 bytes per semaphore.If you can spend few extra KB, which is
usually not a problem on a multi-gigabyte systems used to host oracle databases, you're OK. You need
1 semaphore per oracle process plus 5 per instance (I don't have Steve's book with me, but this was
the number for 8i. If Steve ever decides to update his book for the later versions, my advice is to
grab it while you can). Also, each instance grabs one semaphore set to hold the semaphores for
all processes. That implies that the number of semaphores per semaphore set must be at least as big
as the maximum number of processes that any of your instances may have. The parameter is SEMMSL.
Here is AskTom advice:

http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:454420165038

May the force be with you.

-- 
Mladen Gogala
Oracle DBA
Ext. 121


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