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Re: RAC in NAS

From: Frits Hoogland <frits.hoogland_at_gmail.com>
Date: Sat, 29 Jul 2006 14:27:09 +0200
Message-ID: <fbb8fbcd0607290527w56daf6e9we151237b31780343@mail.gmail.com>


doesn't do a strace on the dbwr and lgwr do what you want to know? it is simple, and it tells you all you want! the calls of synchronous and asynchronous IO are different!

frits

On 7/29/06, 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
>

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Received on Sat Jul 29 2006 - 07:27:09 CDT

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