Re: redo log timing

Ian,
This is one of those where you can get the old "it depends" answer. What type of database is this? What level of transaction activity do you have? How big are your redo logs if you switch every 15 min, 20 min, 30 min? How critical is recovery to the current time to you?

If you don't want the overhead of lots of log switches and you can stand to have a possible loss of 30 minutes of data on a recovery then 2/hr would work. (Possiblity of data loss based on losing all logs and mirror logs in a recovery scenario).

Others may have differing opinions on this, but I normally keep mine running in the 15-20 minute range. The overhead difference between 2 switches/hour and 3 or 4 per/hour is generally not noticeable. It makes for smaller archives which makes the gzip of the log run faster and take up less cpu time. (I run a cron job that compresses the archived logs to save disk space).

On Tuesday 20 March 2001 11:36, you wrote:
>
> Now for an Oracle question. It is often touted that redo logs should
> switch every 15 minutes to 30 minutes. Are these the lower and upper
> limits, should the average time to switch logs be within that range, or
> should the median be between that range?
>
> Ian MacGregor
> Stanford Linear Accelerator
> ian_at_slac.stanford.edu
>
>

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Rodd Holman
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rodney.holman_at_lodgenet.com
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