Re: Size of SGA and kernel parameters

Diego,

There are many different rules of thumb when sizing SGA's. It all depends on who you ask. Is the SGA 1/2 of available RAM, or 1/3 of available RAM? Personally, I feel that it all depends on the usage of your database system. If you have a box with 4GB of RAM, why size the SGA at 2GB or over 1GB if your system only needs an SGA sized at 500MB? You can end up allocating resources to your SGA that are never needed. But there is another side that says if you have the resources available, why not allocate them to the SGA? What is it hurting? It all depends on a lot of factors.

As far as kernel parameters, I am not familiar with HP boxes. But I have worked on both Sun and SG boxes. These unix boxes need to have shared memory allocated in order for Oracle to run. The OS specific installation guides give you information on how to configure the shared memory kernel parameters. Refer to your OS specific installation guide for more information.

For sizing the INIT.ORA parameters, you'll need to adjust a few parameters that will effect your SGA. These include: DB_BLOCK_BUFFERS, SHARED_POOL_SIZE and LOG_BUFFER. There are many other parameters as well. Outside of some basic rules of thumb, no one can answer what values these parameters should have. That all depends on your applications and system load. You'll have to refer to the Oracle Tuning Guide or the variety of 3rd party books that cover Oracle tuning.

HTH,
Brian

Diego wrote:
>
> Hi,
> I have an HP box with 2GB of physical RAM memory. I'd like to extend
> the size of my SGA, I read that I can use up to half of RAM memory for
> Oracle (is that true?). So my idea is to extend the SGA to 1 GB.
> The question is how should I increase the kernel and init.ora
> parameters to arrive to that value? Which are the parameters that I
> should change and which values they should have?
> Thanks a looooooot for your answer. Please if you can anser me to
> dpafumi_at_usa.com
> Thanks
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
 

-- 
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Brian Peasland
Raytheons Systems at
  USGS EROS Data Center
These opinions are my own and do not
necessarily reflect the opinions of my 
company!
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