RE: asynch I/O

And on some platforms, like OpenVMS, async IO isn't an option -- it's the default. :)

Rich
OpenVMS bigot, despite not having any more VMS boxen around... :(

Rich Jesse                           System/Database Administrator
rjesse_at_qtiworld.com                  Quad/Tech Inc, Sussex, WI USA

> -----Original Message-----
> From: Tanel Poder [mailto:tanel.poder.003_at_mail.ee]
> Sent: Friday, September 19, 2003 11:05 AM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: asynch I/O
>
>
> I just hit a description of async IO in Oracle docs, it is very simply
> described there:
>
> <quote>
> With synchronous I/O, when an I/O request is submitted to the
> operating
> system, the writing process blocks until the write is
> confirmed as complete.
> It can then continue processing.
> Asynchronous I/O allows a process to submit an I/O request but to then
> continue processing. It may then check on the result of the
> I/O at a later
> time. It is also possible to submit several I/O requests and
> then collect
> the status of those requests at a later time, thus allowing
> the operating
> system to parallelize any of those I/O operations, where
> possible. Parallel
> processing can reduce the overall time to complete an operation.
>
> Consider an extreme example: Imagine you want to write out
> four data blocks
> to four different files. With synchronous I/O you must submit
> block 1, wait,
> submit block 2, wait, submit block 3, wait, submit block 4,
> and wait. With
> asynchronous I/O, you can submit blocks 1, 2, 3, and 4 and
> then wait for all
> four blocks to complete. Because you gave the operating
> system all four I/O
> requests at once, it can act on all the requests in parallel.
> The total
> response time is only the duration of the longest I/O of the
> four, rather
> than the sum of all four I/O durations.
>
> </quote>
>
> Tanel.
>
> ----- Original Message -----
>
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Friday, September 19, 2003 5:24 PM
>
>
> > Ryan,
> >
> > You can have separate mount points from your server's
> perspective, but
> once you get into the NetApp it's just a pool of disk drives that are
> allocated as necessary by their WAFL (Write Anywhere File
> Layout) system.
> Therefore in reality you get zero benefit.
> >
> > Dick Goulet
> > Senior Oracle DBA
> > Oracle Certified 8i DBA
> >
> > -----Original Message-----
> > Sent: Thursday, September 18, 2003 10:10 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Could you clarify something for me? Are you saying that if I have a
> variety
> > of 'mounts' on our netapp
> >
> > say
> >
> > /mnt1
> > /mnt2
> >
> > I would not benefit by putting my datafiles on seperate
> ones? I thought
> that
> > is where my I/O waits are coming from. Since we have all of
> our datafiles
> in
> > the same directory?

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