Re: RAC in NAS

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