Re: log_buffer settings

Can you guess why so many "noted" authors and tuning experts mention this in their books? How did this myth get started?

Over the years, I'm convinced that the top 3 Oracle tuning books are only 85% correct.

On Sun, 26 Sep 1999 14:00:04 -0400, Thomas Kyte <tkyte_at_us.oracle.com> wrote:

>>Can anyone help out with "realistic" settings for the log_buffer parm, as
>>well as anything else I might want to check?
>>I have kept increasing the log_buffer parm to 16meg now, but still keep
>>seeing the waits below. I changed the log_simultaneous_copies to 16 (2 x
>>#cpu's), but nothing seems to help. The below was from a 2 hour window when
>>normal activity was taking place. It's an OLTP system (400 concurrent
>>users), Oracle 7.3.4, aix 4.3.2 (4 gig of ram), sga of about 700 meg, 250
>>meg of shared pool. The Oracle manuals state that increasing the log_buffer
>>beyond 1 meg does no good, but I've heard otherwise. It hasn't made any
>>difference for me... There must be something I'm missing.
>>
>
>reduce that log buffer size, get it back down into KILOBYTES, not megabytes.
>
>increasing the log buffer will not help (and can in fact hurt).
>
>the redo log space requests are not waits for space in the redo log buffer -
>they are waits for space in the online redo logs themselves. (some documentation
>erroneously tells you to increase the log_buffer -- it is wrong, increasing the
>log_buffer -- as you have seen -- will have no effect on this).
Received on Sun Sep 26 1999 - 21:14:47 CDT