Re: 11i RAC question
- From: Anand Rao <panandrao@xxxxxxxxx>
- To: racdba@xxxxxxxxxxxxx
- Date: Wed, 31 Aug 2005 09:40:16 +1000
Hi Amir,
some more questions..
1) Are you using ASSM? if not, use it now.
2) have you checked the statspack reports for logical io problems?
what objects do you see there?
workflow tables, index branch blocks and leaves are most common. what
modules are you using? fnd tables will have a lot of logical io.
3) Are you caching sequences?
there are many serious design issues in Apps 11i which has caused a
lot of trouble, so let us know what exactly is your 'performance'
issue.
just increasing CPU priority will take care of the issue for some
time, then you could be back to square one once you run out of CPU
cycles. You cannot just keep adding CPUs for that reason alone.
anand
On 31/08/05, Anand Rao <panandrao@xxxxxxxxx> wrote:
> Increase CPU Priority for LMS. This is definitely the way to go. no
> doubts at all.
>
> you need to give us more info on the machine config, enviornment details, etc.
>
> I have seen quite a bit of improvement on many RAC systems, mainly 11i
> with RAC on large E15K clusters and HP clusters when we increase LMS
> priority.
>
> Don't forget to increase LGWR priority. I would always suggest that
> all Oracle background processes (especially LGWR, SMON, DBWR) should
> run on a higher priority and should not be fighting for CPU with other
> processes. On RAC, LMON, LMD and LMS priority should be higher than
> any other Oracle process. On Solaris, place them on Real Time
> priority. Talk to your system admin if you don't understand the
> various priorities.
>
> Don't use a value more than 8 for db_file_multi_block_read_count
> UNLESS you are a total datawarehouse or something like that. I have
> learnt it the hard way that 8 gives the best respone. 4 is also good
> but that depends on your application. I am running my current 4-node
> AIX RAC cluster with a value of 4 for MBRC.
>
> In your statspack,
>
> What is the value of 'Ratio of current block defers' and 'global cache
> defers'?
>
> by setting _gc_defer_time you are treating the symptom and not the cause...
>
> let me know
> cheers
> anand
>
>
> On 30/08/05, Ravi_Kulkarni@xxxxxxxx <Ravi_Kulkarni@xxxxxxxx> wrote:
> >
> > Hamid,
> >
> > Curious - what are the values your max_commit_propagation_delay &
> > _fairness_threshold ?
> > Also, can you pass on the TAR# (mail me offline, if you wish)
> >
> > Thanks,
> > Ravi.
> >
> > ________________________________
> > From: racdba-bounce@xxxxxxxxxxxxx [mailto:racdba-bounce@xxxxxxxxxxxxx] On
> > Behalf Of Hameed, Amir
> > Sent: Tuesday, August 30, 2005 8:37 AM
> > To: racdba@xxxxxxxxxxxxx
> > Subject: RE: 11i RAC question
> >
> >
> >
> > 9.2.0.6 (64-bit) on Solaris. This question is in continuation of the problem
> > that I had sent a note out to this DL last Friday. I finally opened a TAR
> > last night with Oracle as it seemed like an Oracle issue to me.
> >
> > ________________________________
> > From: racdba-bounce@xxxxxxxxxxxxx [mailto:racdba-bounce@xxxxxxxxxxxxx] On
> > Behalf Of Sudhi
> > Sent: Tuesday, August 30, 2005 9:29 AM
> > To: racdba@xxxxxxxxxxxxx
> > Subject: RE: 11i RAC question
> >
> >
> >
> >
> >
> >
> > Increasing the priority of LMS/LMD processes is a known thing for
> > performance. I'm not sure about the "_gc_defer_time". KG or Anand should be
> > aware of it.
> >
> >
> >
> > BTW what version of RAC ?
> >
> >
> >
> > Thanks,
> >
> > -Sudhi.
> >
> >
> >
> > ________________________________
> >
> >
> > From: racdba-bounce@xxxxxxxxxxxxx [mailto:racdba-bounce@xxxxxxxxxxxxx] On
> > Behalf Of Hameed, Amir
> > Sent: Tuesday, August 30, 2005 6:55 PM
> > To: racdba@xxxxxxxxxxxxx
> > Subject: 11i RAC question
> >
> >
> >
> > Is there anyone in this DL running 11i with RAC? If yes then can you please
> > tell me if you had to make the following settings to address some cache
> > fusion issues:
> >
> > + alter system set "_gc_defer_time"=0;
> > + Increase the priority of LMS process ( renice -n -p <PID of LMS process> )
> >
> > I have a TAR opened with Oracle and they are suggesting this solution. I
> > want to make sure that the solution is not custom and is a generic one and
> > has just not documented. Any feedback will be appreciated.
> >
> > Thanks
> > Amir
>
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