Re: undo segments online causing performance problems.

And how did you determine UNDO segments is your problem...?



On 12/29/05, The Human Fly <sjaffarhussain@xxxxxxxxx> wrote:
>
> Hello Everbody,
>
> Our share trading application database, patch set 9205, running on AIX
> 5.3 64bit with 12CPU + 30 GB Memory,. Everyday, during trading
> beginning hours, end-users complains that the database is performing
> very slow, like hang stage for some times. We noticed that Oracle has
> brough many undo segs. online.  As per Oracle Support, we have set an
> databases event '10511' for SMON to prevent taking unused undo segs
> offline, i.e. keeping always undo segs online. But, this event brought
> some other problems. SMON is not offlining the undo segs. rather, what
> we see is that a lot of expired undo segs and everyday brings arond 40
> undo segs. online and still the same story repeates. When we count for
> online undo segs from dba_rollback_segs, what we see is around 100+
> undo segs. are online.
> We have set session parameter around 1400 and our undo tablespace
> size is  6.6 gb and undo retention is set to default, i.e. 3 hrs.
>
> Is there any one facing the similar kind of problem. If so, is there
> any work around. We are thinking of going back to MUM, where we create
> around 100 rollback segments manually and size them accordingly. Is
> that a good idea?
>
> Thanks for your time.
>
>
>
>
> --
> Best Regards,
> Syed Jaffar Hussain
> OCP 8i & 9i DBA,
> Banque Saudi Fransi,
> Saudi Arabia
>
> ----------------------------------------------------------------------------------
> "Winners don't do different things. They do things differently."
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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