Re: Default value for log_buffer parameter

David Hollenberg wrote:
> Using Oracle 10.2.0.1.0 on Solaris 9.

...
>
> Documentation says that redo log buffer size is controlled manually
> (not part of automatic sizing) and has a default value of "512 KB or
> 128 KB * CPU_COUNT, whichever is greater". Machine has 4 CPUs, so log
> buffer size should be 512 KB. Documentation bug or code bug?

That comes from the Reference manual. According to Note:270065.1, "The manually tuned components will always have the value assigned from SGA_TARGET and lowering or increasing SGA_TARGET will not affect them." This means that if ASMM is enabled, size of components such as log_buffer is still controlled by sga_target, only that their size won't change after initial allocation. In the same note under "Important points to remember when using this feature": "SGA_TARGET will affect both manually tuned and automatically tuned components... Manually Sized SGA Components that Use SGA_TARGET Space SGA Component Initialization Parameter
The log buffer LOG_BUFFER
..."

(Ignore streams_pool_size since it changes to automatically sized beginning with 10.2)

I think both Reference and Performance Tuning guide need to be modified, and explain the word "manually" more clearly.

Yong Huang Received on Fri Oct 28 2005 - 09:10:38 CDT