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Re: RAC in NAS

From: Christo Kutrovsky <kutrovsky.oracle_at_gmail.com>
Date: Mon, 31 Jul 2006 14:01:58 -0400
Message-ID: <52a152eb0607311101t3e640627h71e4bf511caa7e13@mail.gmail.com>


strace the dbwriter process and look for io_submit() vs. pwrite().

disk_async_io applies to RMAN backups.

I hope it's not answered further down, i am still reading this.

-- 
Christo Kutrovsky
Senior Database/System Administrator
The Pythian Group - www.pythian.com
I blog at http://www.pythian.com/blogs/


On 7/28/06, Mark Brinsmead <pythianbrinsmead_at_gmail.com> wrote:

> Nuno,
>
> You are only *half* right, I fear.
>
> Actually, at least one of -- and perhaps both -- MetaLink and Werner
> describe more or less
> the same caveat, that is: applications *other* than Oracle may be
> responsible for the non-zero
> counts in slabinfo.
>
> But here's the half where you're wrong. (Or at least, not completely
> "right".) Those hypothetical
> "other" applications can just as easily be resposibly for the *increases* in
> the slabinfo stats as
> they are they would be for "non-zero" values. After all, those values had
> to increase from zero
> *some* *time*, didn't they. ;-)
>
> Anyway, you are correct about this: I am still unaware of a simple way
> to prove *conclusively*
> that a database is actually using Asynch I/O. But (on a good day) I now at
> least know how to
> prove that it is *not*. (Or at least that *no* databases *are*. Sadly,
> multiple database on the
> same host muddy the water even more.)
>
> If anybody out there can tell me of a simple (and reliable) test that
> *proves* a database is using
> Asynch I/O, I'd like to hear about it...
>
> In the meantime, it has (happily) met my purposes to be able to prove the
> negative.
>
>
>
> On 7/28/06, Nuno Souto <dbvision_at_iinet.net.au> wrote:
> > Mark Brinsmead wrote,on my timestamp of 28/07/2006 1:39 PM:
> >
> > > (Almost) just for chuckles, I opened an SR with Oracle support, asking
> > > questions like "how can
> > > I test whether my DB is doing Asynch I/O on Linux?" and "knowing that
> > > Asynch I/O is unsupported,
> > > what are the risks of doing so anyway?". After almost two weeks, the
> > > questions are unanswered,
> > > even though I was able to answer them myself with less than an hour of
> > > surfing Metalink and Google.
> >
> > yes, there is a note in metaclick explaining how to check.
> > But it's not complete, neither is werner's site:
> > you check for those counters in /proc/slabinfo being
> > non-zero *AND* changing in value when you startup Oracle!
> > There might be *other* software around already using aio
> > and just having them as non-zero is not enough to say
> > Oracle is using it.
> >
> > DAMHIKT...
> >
> >
> > --
> > Cheers
> > Nuno Souto
> > in (finally) sunny Sydney, Australia
> > dbvision_at_iinet.net.au
> > --
> > http://www.freelists.org/webpage/oracle-l
> >
> >
> >
>
>
>
> --
> Cheers,
> -- Mark Brinsmead
> Staff DBA,
> The Pythian Group
> http://www.pythian.com/blogs
-- Christo Kutrovsky Senior Database/System Administrator The Pythian Group - www.pythian.com I blog at http://www.pythian.com/blogs/ -- http://www.freelists.org/webpage/oracle-l
Received on Mon Jul 31 2006 - 13:01:58 CDT

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