RE: Solaris 10 shmmax

Ahh...but I didn't say that SHMMAX doesn't matter. I'm sure that SHMMAX does matter and that there are values of SHMMAX for which Oracle simply won't start. For 10gR2 on 64-bit Sparc Solaris, Oracle recommends 4,294,967,295. If you go w/ that value of SHMMAX and you are on a box w/ lots of RAM and more than 4GB of RAM, Oracle will start with multiple shared memory chunks making up the SGA. This is what I'm saying doesn't matter.  

All I'm saying is, if you have SHMMAX properly set to what Oracle recommends and your SGA ends up in multiple shared memory chunks, it doesn't matter. It's not important, it's not worth worrying about.  

-Mark  

-- 
Mark J. Bobak 
Senior Oracle Architect 
ProQuest/CSA 

"There are 10 types of people in the world:  Those who understand
binary, and those who don't." 

 



________________________________


From: amonte [mailto:ax.mount_at_gmail.com] 
Sent: Monday, March 26, 2007 2:20 PM
To: Bobak, Mark
Cc: kevinc_at_polyserve.com; Hameed, Amir; oracle-l_at_freelists.org
Subject: Re: Solaris 10 shmmax


Hi

The box I have installed were Sun Blades, with four AMD Opteron Dual
Core CPUs and 8GB Memory.

Mark if shmmax does not matter I dont understand why it is a requirement
in Oracle 10gR2 Installation Guide .... 


On 3/26/07, Bobak, Mark <Mark.Bobak_at_il.proquest.com> wrote: 

	Does it really matter if your shared memory is in one chunk or
not?  I seem to remember a bit of misinformation that used to float
around was that if the SGA was not in a single shared memory chunk, then
ISM was disabled.  Turns out that isn't true.  I can't think of any
reason why it would be important for the SGA to be in one contiguous
memory chunk.
	 
	 
	-Mark
	 

	-- 
	Mark J. Bobak 
	Senior Oracle Architect 
	P roQuest/CSA 

	"There are 10 types of people in the world:  Those who
understand binary, and those who don't." 

	 



________________________________


	From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Kevin Closson
	Sent: Monday, March 26, 2007 1:09 PM
	To: Hameed, Amir; ax.mount_at_GMAIL.COM; oracle-l_at_freelists.org
	Subject: RE: Solaris 10 shmmax
	
	
	The 490 is a flat memory box and the Solaris port is smart
enough to behave correctly.

	 

	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)?

		 

		 



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