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Home -> Community -> Mailing Lists -> Oracle-L -> Re: How to enable Async I/O on Solaris
Thanks a LOT for the article!
< The good news, from an application standpoint, is that the question of whether or not there is kaio support for a given combination of storage devices, volume managers, and file systems is transparent: If kaio support exists, it will be used. If it doesn't, the original library-based async I/O will be used. Applications don't change in order to take advantage of kaio. The system figures out what is available and allocates accordingly. >
So, according to the article, the answer is:
Yes, aio works in Solaris, but it depends on your hardware + software ( can
be tested in OS level ) and it will work in Oracle if the regarding init
parameter is enabled.
Am I missing something?
Michael
> I was going to wait until tonight to send out the link to the
article(s),
> but I got a few emails showing interest, so I tracked one of the Sunworld
> InsideSolaris articles down. I'm pretty sure I have a link to another
> article at home that explains it a little better, but for those of you
that
> are interested:
>
>
http://www.sunworld.com/sunworldonline/swol-07-1998/swol-07-insidesolaris.ht
> ml
>
>
> Jeff S
>
> -----Original Message-----
> Sent: Monday, November 13, 2000 11:06 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Solaris does seem to support AIO in a bastardized manner...I've been
doing
> some research on it at home (which is where I have a bunch of links to
> articles that discuss it). Basically, the kaio system call gets posted
and
> on a raw system works fine...on a cooked system it generates the same
error
> message a few times. Digging a little deeper on this (after reading
through
> an article on the subject...I'll have to post that to the list tonight), I
> noticed that each error created a new light-weight process thread that
> started doing other work. These lwp threads would each run their course
and
> then generate a normal write system call (pwrite64 in the more recent
> versions of Solaris). If you take a look at the system calls from the
DBW0
> process, it just looks like the asynchronous I/O call (kaio) is just
failing
> and then reverting to normal writes, but if you look at the lwp level, you
> can see that each one of these is being handled by multiple lwps. It is
> essentially a "mock" asynchronous I/O, and it's probably not as efficient
as
> creating multiple DB writers like Gaja suggests, but it does seem to work.
> I'll try to send the article out to the list later on if anyone is
> interested. It is basically a Sun article that explains in more detail
how
> this mock AIO works. Just some more stuff to think about...
>
> Jeffery Stevenson
> Chief Database Geek
> Medical Present Value, Inc.
> Austin, TX
>
> -----Original Message-----
> Sent: Monday, November 13, 2000 9:50 AM
> To: Multiple recipients of list ORACLE-L
>
>
> It is supported for raw devices and Quick I/O Veritas files.
>
> -----Original Message-----
> Sent: Friday, November 10, 2000 5:26 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Jared,
>
> Do you mean it works pretty bad or it is not supported on Solaris? Does
it
> work on Solaris at all?
>
> Thank you,
> Michael
> www.atelo.com
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Friday, November 10, 2000 16:39
>
>
> > On Fri, 10 Nov 2000, Bill Conner wrote:
> >
> > > At 11:30 AM 11/10/00 -0800, you wrote:
> > > >The default for disk_async_io is true.
> > > >
> > > >Either async i/o is support or not. T'ain't supported on
> > > >Solaris unless you have raw devices.
> > >
> > > This is news, solaris used to support async i/o on cooked
> > > devices when did this change?
> >
> > Well, it's never actually worked on cooked filesystems.
> >
> > Jared
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Jared Still
> > INET: jkstill_at_bcbso.com
> >
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> --
> Author: Jeffery Stevenson
> INET: jeff_at_mpv.com
>
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Received on Mon Nov 13 2000 - 15:10:45 CST
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