Re: Relationship between Oracle log file size and Oracle performance

On Mar 7, 7:56 am, "jshen...._at_gmail.com" <jshen...._at_gmail.com> wrote:
> hi,
>
> Last day, I cleared our Oracle DB server network listener's log
> file, which is around 1.7GB.
>
> After doing that, I found I/O queue size decrease A £Ì£Ï£Ô, while 'sar
> 3 5' shows wio keeps be to higher than 65%.
>
> The oracle version is 8.1.7 running on HP-UX 11i.
>
> I want to tune DB performance further. So, I want to know whether
> this relationship between Oracle perfromance and network listener log
> file size ? Is there any relationship between Oracle performance and
> redo log file size? (Our current redo log file size is 500MB, there
> are two redo logfile defined, show I try to increase the size to
> 1GB ? )
>
> each word will be highly appreciated.
>
> Joe

(I concur with Sybrand. That said,)

There are many things that affect Oracle performance. In general, a 500MB redo log shouldn't affect it too much. The big question is how often do the logs switch? Many places base their service level agreements on not losing more than a certain amount of data in a disaster. If your logs are switching every 30 seconds, you may indeed have performance issues. If they are switching every 24 hours, you may have a hole in your recovery strategy. If they are switching every 20 minutes exactly and are widely varying sizes, you may have a cron controlling the granularity.

After you go through the concepts manual, check out the performance manual. While there are some old wives tales in there, much of the information is good. There are a number of different methodologies used for tuning, but you are using an ancient version that is no longer supported, and your second priority is to get away from that.

Your first priority shouldn't be tuning, it should be understanding what level of risk your database is at. If you don't have a qualified DBA available, you are in a pretty scary situation.

Some other resources: http://www.dbaoracle.net/readme-cdos.htm

jg

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