Re: tuning redo logs

In article <2Vyn2.305$Za3.2692_at_news13.ispnews.com>,   "Osvaldo Robles" <orobles1_at_coqui.ney> wrote:
> I would like to know if there is a formula or a method to determine the
> number of redo logs necessary for a database that handles about 16 million
> records.
>

I do not know of any formula, but I can offer the following advice. Look in the alert log and count the number of redo log switches that you do in a day and check to see how close together they are. Multiply the log size times the number of logs then divide this number by the number of logs you think would be reasonable for you database.

I like to use 24 which is one log switch per hour on average, but you can go with a larger or smaller number based on which is more important: fast restart after crash, which wants smalerl logs, or better rdbms performance because of fewer forced flushes of the buffer cache due to log switch induced checkpoints which means bigger redo logs. Our database is stable so I want the fewer checkpoints.

Do not forget to check your redo latch hit ratio, and it is not uncommon for the size of the redo log buffer to need increasing in the init.ora via log_buffer parameter.

Mark D. Powell

-----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own Received on Fri Jan 15 1999 - 08:43:49 CST