[Hrgeeks] kernel.shmmax

[Erin]

Thanks for the input gentlemen. I now am educated. Rock.

Erin

On Apr 9, 2010, at 1:27 PM, Erik Beebe <erik at mrhz.net> wrote:

> Remember that shmmax is just setting the maximum possible shared  
> memory
> segment - not how much memory you're actually reserving.  You'll do  
> that
> when you configure the SGA in Oracle.  How large of an SGA you want  
> may be
> left up to trial and error, but remember that the shadow processes  
> (ie.
> the ones spawned per connection) use memory outside of the shared  
> memory
> segment that you've reserved, so plan for that when deciding how  
> much to
> leave remaining.
>
> Also, Google for 'oracle rhel hugepages' or something similar, and
> consider using them, as they'll provide 2MB pages (vs. 4k), which  
> makes
> for a much smaller page table with large memory allocations.
>
> PS. The Linux virtual memory manager isn't that smart - consider  
> setting
> vm.swappiness to 0 for a dedicated database server.
>
> -Erik
>
> On Fri, 9 Apr 2010, Matt Glaves wrote:
>
>> As long as it's a dedicated DB box I think RAM-2GB left over for  
>> the base OS
>> is what I'd start with.
>>
>> matt
>>
>>
>> On Fri, Apr 9, 2010 at 12:29 PM, Erin <ewinningham at gmail.com> wrote:
>>
>>> Ok. I claim defeat. Will someone please explain kernel.shmmax and
>>> kernel.shmall to me?  Specifically in relation to running Oracle on
>>> RHEL5 64bit. It seems the OS sets it to 64GB even though the server
>>> has 32GB of RAM. Tuned to RAM + reommended swap perhaps?  From  
>>> what I
>>> can tell Oracle recommends RAM - 2GB on 64bit systems.
>>>
>>> Discuss.
>>>
>>> Erin
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