Recommended Redo Log size

Wrong !

But thanks for co-operating.

It's a reasonable guess, of course - clearly the system must have seen a higher average rate of change over that hour (and the following one) - but that doesn't mean the system was under stress at any particular time.  The only thing this report can tell you is that the pattern isn't the same as usual - and when the pattern hasn't changed you might have a problem, and when the pattern has changed you might not have a problem.

The point at which the most significant redo waits appeared was from 20:58 to 21:02 when there were 10 log file switches in just over 3 minutes. As Cary Millsap puts it: you can't derive detail from a summary.

Regards

Jonathan Lewis

2995489 wrote:

Hi,

yes i used the query ( V$ARCHIVED_LOG ). I find mininum 6 switschs/hour all the day.

But you still haven't demonstrated that log switches -- regardless of how frequently they occur -- actually causes a problem in your business.  The key is NOT the rate at which log switches occur, the key is measured wait events related to log switches.  Take some meaningful statspack reports and see how often those wait events appear in the 'top 5' list.  And even then you need to apply a bit of reason, as there will always be a 'top 5' events.

How much effort is justified to reduce the average response time of an OLTP transaction by 90%?   (Really?  what if the averages response time is already 0.05 seconds?)

How much effort is justified to reduce the run time of a nightly batch job from 5 minutes to 2 minutes?

How much effort is justified to reduce the run time of a nightly batch job from 2 hours to 30 minutes, if no other process is found to ever be waiting on completion of the batch job?