Re: Help: huge amount of redo log switches

"Howard J. Rogers" wrote:
> <<snipped>>
> > > I tried resizing(increasing and decreasing) log_buffer and redo log file
> > > size but it doesn't help.
>
> I suspect that you should qualify that statement. You increased the size of
> your redo logs and it made precisely NO difference??? I suspect you are
> being economical with the truth, or someone is playing you false. If it
> takes 3 minutes to fill up 4M, then doubling the log file size would mean
> (ceteris paribus) that it would take 6 minutes to activate a log switch.
> Yet you claim ZERO difference?
>
> The ONLY reason there could be zero difference in the time taken to fill up
> the double-sized logs is if the transaction rate had just doubled as well.
> <<snipped>>

Howard,
I agree with everything you said but this, depending on how you define transaction rate. If you look at transaction rate from a user transaction standpoint, it's possible that the logs were the bottleneck and you could fill double the size in the same time if the rest of the system was fast enough with the bottleneck removed. It would be the same transaction rate with higher throughput and lower response time. I doubt this is the case in this instance. FYI, we had log switches every minute on one of our large SAP systems with 25MB logs. The switch to 50MB didn't really help because the log switches were the bottleneck and we now have 100MB logs. When our large batch processes run we create gigs of logs an hour.

Big Al Received on Wed Aug 09 2000 - 00:00:00 CDT