Re: Log File Switch Completion

  • From: ja_morcillo_servext_rsi@xxxxxxxxxxxxx
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Mon, 22 Jul 2013 14:47:42 +0200

Hello!
Sorry for not being more specific!

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@xxxxxxxxxxxx>
Para:   oracle-l@xxxxxxxxxxxxx
Fecha:  22/07/2013 14:19
Asunto: Re: Log File Switch Completion
Enviado por:    oracle-l-bounce@xxxxxxxxxxxxx



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@xxxxxxxxxxxx

On 22/07/2013 8:14 PM, ja_morcillo_servext_rsi@xxxxxxxxxxxxx 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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