Re: Changing redo log file size

cvr_at_global.co.za wrote:
>
> The size of my redo log files is 1M - with 2 redo log groups. We are
> producing about 30M of redo per day.
>
> 1) How can I resize the redo log files?
>

Create new ones of the size you want and drop the old ones. The manual has a good explanation on how to do this.

> 2) What would be good values for redo log file size and number
> of redo log groups?

In general, you want to size your redo logs in such a way that you do not cause a redo log switch every few minutes. The reason for this is that a redo log switch involves a compete data buffer checkpoint, which is a lengthy operation, particularly with today's very large SGAs.

So, aim for a redo log switch every hour or so. How do you time them? Easy, look into the alert log file, each redo log switch generates a log entry there with a timestamp. Create progressively larger redo log files until you only get a switch every now and then. Don't go much larger than 50Mb though: there are other issues that take over after that size of redo log is reached. Too complex to go into here. Just bump them up from whatever you got until you get a reasonable gap between redo log switches and leave it at that. There is not much more you can do with their sizing in terms of tuning, so don't dwell for too long with that one.

>
> C van Rensburg

Pleasure

Nuno Souto
nsouto_at_acay.com.au Received on Sun Aug 31 1997 - 00:00:00 CDT