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Re: RAC in NAS

From: Frits Hoogland <frits.hoogland_at_gmail.com>
Date: Sat, 29 Jul 2006 18:40:11 +0200
Message-ID: <fbb8fbcd0607290940j3bf4fe4cl6322394f70be0ccc@mail.gmail.com>


exactly my point!

I've seen oracle doing async IO with the 2.4 kernel doing other system calls (the kludgy stuff you mentioned), and oracle doing async IO with the 2.6kernel (io_submit system call).

Ever looked at orion in conjunction with linux? It doesn't seem to do async IO.

frits

On 7/29/06, Kevin Closson <kevinc_at_polyserve.com> wrote:
>
> >> on the other hand, if the system call is the same, what
> kind of magic is involved which makes oracle do asynchronous IO? The
> system call must tell the operating system what kind of IO it wants to
> do, either by doing a call which implies the kind of synchronousity, or
> by setting a flag which alters the synchronousity.
>
>
> ...but the calls are not the same. If you strace 10g DBWR, after linking
> in
> libaio and setting filesystemio_options=direcIO, you will see
> io_submit(2)
> calls which are new to 2.6 kernel. There really was no "real" async IO
> prior to the 2.6 kerenl. There was some kludgy stuff piggy-packed on
> the socket interface of all things, but it was crazy.
>
> Then , of course, if $ORACLE_HOME/lib/libodm* is a real ODM library you
> get
> async IO regardless of what libaio is and regardless of what init.ora
> parameters you set...when ODM is linked in, all the "async*" init.ora
> params
> are no-ops and filesystemio_options doesn't do anything either. You just
> get
> async IO
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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Received on Sat Jul 29 2006 - 11:40:11 CDT

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