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Re: multiblock read count question

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Thu, 21 Jun 2001 21:08:50 +0100
Message-ID: <9gtk75$841$1@news.chatlink.com>

They are buffered unless set explicitly otherwise in /etc/vfstab (under Solaris)

hth
connor

--
==============================
Connor McDonald

http://www.oracledba.co.uk

"Some days you're the pigeon, some days you're the statue..."
"Rob K" <robkato_at_earthlink.net> wrote in message
news:3G6Y6.22725$aV1.2257238_at_newsread1.prod.itd.earthlink.net...

> I believe the filesystem I/O is buffered using Veritas. Is there an easy
way
> to find out?
> "Yong Huang" <yong321_at_yahoo.com> wrote in message
> news:b3cb12d6.0106201048.12d3a771_at_posting.google.com...
> > This is what Steve Adams says:
> >
> > This is what the Ixora web tip on multiblock reads at
> > http://www.ixora.com.au/tips/creation/multiblock.htm says on the matter
...
> >
> > "Unfortunately, if you use buffered I/O the operating system will
service
> > multiblock reads as a series of small I/O operations anyway and the only
> > benefit
> > from multiblock reads will be a small saving in CPU usage. In this case
the
> > multiblock read count should be approximately equal to the typical track
length
> > to take advantage of track buffering and no larger lest the optimizer be
> > deceived."
> >
> > The key word there is "buffered". If your filesystem is able to do
direct I/O,
> > and is configured to do so, then the large multiblock read principle
applies.
> > But, if your filesystem I/O is buffered, then there is very little to
gain.
> >
> >
Received on Thu Jun 21 2001 - 15:08:50 CDT

Original text of this message

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