Re: enq HW - contention waits

There are not many things available for ASSM but, two general solutions for HW lock contention on ASSM are
- Use large extent size like uniform 10M - Preallocate extents before concurrent inserting

Dion Cho

2008/4/19, Ravi Gaur <ravigaur1_at_gmail.com>:
>
> Hello Rajiv,
> Yes, we use ASSM. I think I'll have to wait for the situation to recur for
> the 10045 trace. I can provide the AWR for the 30min interval when this was
> happening, if that helps.
>
> Thank you,
> - Ravi
>
> On Fri, Apr 18, 2008 at 7:03 PM, Rajeev Prabhakar <rprabha01_at_gmail.com>
> wrote:
>
> > Hello Ravi,
> >
> > Are you using ASSM (auto OR manual) ? Can you take a 10046
> > trace for one of those sessions which is waitng on the "enq: HW -
> > contention" and tell us about the kind of blocks that are showing/
> > experiencing these kinds of waits and any other observations that
> > you can make from those traces ?
> >
> > -Rajeev
> >
> > On Fri, Apr 18, 2008 at 4:33 PM, Ravi Gaur <ravigaur1_at_gmail.com> wrote:
> > > Greetings,
> > >
> > > We have a production database running on RAC (4-node) (10.2.0.3 on
> > Solaris
> > > 10) and I'm noticing a lot of waits on "enq: HW - contention". Doing a
> > bit
> > > of researching tells me that it is related to HWM extensions
> > (concurrent
> > > inserts). We have no control on the application so I wonder what could
> > be
> > > done from the database end to tune this up (if anything). Here's what
> > I see
> > > from the AWR during the time it showed up --
> > >
> > > Top 5 Timed Events
> > > EventWaitsTime(s)Avg Wait(ms)% Total Call TimeWait Class
> > > CPU time 7,148 43.5
> > > enq: HW - contention67,0345,2637932.0Configuration
> > > SQL*Net break/reset to client61,0061,504259.2Application
> > > db file sequential read152,43188565.4User I/O
> > > gc cr block busy34,315490143.0Cluster
> > > Any help is deeply appreciated!!
> > >
> > > TIA,
> > > - Ravi Gaur
> >
>
>

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