Re: Shared Pool vs Buffer Cache with ASMM

Hi,

The default algorithm of ASSM is that memory is stolen from the buffer cache if the shared pool is stressed.
However this default behaviour can be changed by setting _memory_broker_shrink_heaps=30
The default value for the above parameter is 0

If you want to continue using this feature you might want to set a minimum value for your buffer cache so that memory does not shrink to below this value.

HTH,

Fairlie

Richard Saints <saints.richard@gmail.com> wrote:

Hello to you all,

I've a mobile application that uses Oracle Lite 10g ( 10.2.0.2) as mobile server and Oracle Database Server 10g release 1 (10.1.0.2) as the repository database. Both of these components are installed on servers with Microsoft Windows 2000 Advanced Server.

My question is related with the repository database:

We use Automatic Shared Memory Management and have a SGA target = to the SGA Max Size = 1336Mb. ASMM always gave a bigger slice of memory to the Buffer Cache (about 70%), but in the last 2 weeks I noticed that the value of the Shared Pool started to increase and now it's bigger than Buffer Cache (a slice of 49,7%).

Here's my current situation:

Shared Pool 664 Mb

Buffer Cache 648 Mb

Large Pool 8 Mb

Java Pool 8 Mb

Other 8 Mb

I have some knowledge of Oracle Database Server Architecture, but I'm being able to interpret this behavior or why this is happening. Can anyone give me some help or some ideas ?

It's also important to say that we have been experiencing some performance problems in the last two weeks. We are also having a bigger volume of data.

Thanks for all your attention.

Best Regards,

Ricardo Santos

PL/SQL Analyst/Developer

Fairlie Rego
Senior Oracle Consultant

http://el-caro.blogspot.com/

M: +61 402 792 405

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Re: Shared Pool vs Buffer Cache with ASMM

fairlie rego

2007-07-06