Re: Problem with Asus P4C800-DX and P4 -Northwood-

[Jesper Juhl]

On 7/25/05, Erik Mouw <erik@xxxxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Jul 25, 2005 at 09:51:49PM +0200, Andreas Baer wrote:
> >
> > Willy Tarreau wrote:
> > >On Mon, Jul 25, 2005 at 03:10:08PM +0200, Andreas Baer wrote:
> > >>Here I have
> > >>
> > >>        /dev/hda:  26.91 MB/sec
> > >>        /dev/hda1: 26.90 MB/sec    (Windows FAT32)
> > >>        /dev/hda7: 17.89 MB/sec    (Linux EXT3)
> > >>
> > >>Could you give me a reason how this is possible?
> > >
> > >
> > >a reason for what ? the fact that the notebook performs faster than the
> > >desktop while slower on I/O ?
> >
> > No, a reason why the partition with Linux (ReiserFS or Ext3) is always
> > slower
> > than the Windows partition?
> 
> Easy: Drives don't have the same speed on all tracks. The platters are
> built-up from zones with different recording densities: zones near the
> center of the platters have a lower recording density and hence a lower
> datarate (less bits/second pass under the head). Zones at the outer
> diameter have a higher recording density and a higher datarate.
> 
It's even more complex than that as far as I know, you also have the
issue of seek times - tracks near the middle of the platter will be
nearer the head more often (on average) then tracks at the edge.

For people who like visuals, IBM has a nice little picture in their
AIX performance tuning guide :
http://publib.boulder.ibm.com/infocenter/pseries/index.jsp?topic=/com.ibm.aix.doc/aixbman/prftungd/diskperf2.htm


-- 
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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