Re: Log File Switch Completion

We are under 11.2.0.2.0 and Linux 2.6.18-238.el5, three nodes RAC.

The thing is that we experienced a RAC hang. In node 1 and 2 we found one event using around 25% of the time: "enq: SQ - contention" and in node 3 the event: "row cache lock"
using 36.50% of the time and the event "log file switch completion" using 28.72% of the time.

We increased sequences cache but now we want to know why "log file switch completion" event showed up in node 3, here is where support told us to reduced the size of
our log files...but we think they are not right!

bd is a pure data warehouse.

Thanks a lot!
José  

De: Nuno Souto <dbvision_at_iinet.net.au> Para: oracle-l_at_freelists.org
Fecha: 22/07/2013 14:19
Asunto: Re: Log File Switch Completion
Enviado por: oracle-l-bounce_at_freelists.org

Why would support be worried about 1GB log file beats me. I assume you are on archive redo log mode, and that you are concerned with waits on that event?
It isn't necessarily bad. I've been on 1GB redo logs in my DW for nearly 5 years now and no sweat.
It is all very contingent on what your db is doing. Is it for EBS or some other DSS/OLTP application?
If so then yes, I'd be concerned with reducing the switch completion event wait. But it all hinges on how much wait you are experiencing. Some numbers, release levels, OS levels, etc, would be welcome. As well, the nature of the db and its applications.

-- 
Cheers
Nuno Souto
dbvision_at_iinet.net.au

On 22/07/2013 8:14 PM, ja_morcillo_servext_rsi_at_cajarural.com wrote:
> Hi fellows! We think the event  "Log File Switch Completion" must be


 > independent of log size but people from support say that it is

 > dependent os log size and as we have a redo log size of 1Gb they want

 > us to reduce it!

 >

 > What do you think about it?

 >

 > Thanks! José

 >




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