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Date: Tue, 26 Nov 2002 13:48:46 +0100
From: Adrian Bunk <bunk@fs.tum.de>
To: Tomas Szepe <szepe@pinerecords.com>
Cc: Dennis Grant <trog@wincom.net>, linux-kernel@vger.kernel.org
Subject: Re: Identifying/activating faster ATAxx modes (WAS kernel config tale of woe)
Message-ID: <20021126124846.GK24796@fs.tum.de>
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On Tue, Nov 26, 2002 at 01:15:45PM +0100, Tomas Szepe wrote:

> > > > /dev/hda:
> > > > 
> > > >  Model=Maxtor 6E030L0, FwRev=NAR61590, SerialNo=E106SZLE
> > > >  Config={ Fixed }
> > > >  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57
> > > >  BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=16
> > > >  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=60058656
> > > >  IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
> > > >  PIO modes:  pio0 pio1 pio2 pio3 pio4
> > > >  DMA modes:  mdma0 mdma1 mdma2
> > > >  UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6
> > >...
> > > This is weird.  Your disk seems to be set up for udma6 (UATA133),
> > > which should provide for transfer rates of at least 40MiB/s.
> > >...
> > 
> > The information in "hdparm -i" shows the identification info of the
> > drive. It doesn't show whether DMA is actually used (you need
> > "hdparm -v" for this)...
> 
> While this is true, I fail to see why the -i output would report
> udma6 as being the current transfer mode instead of a pio one if
> DMA were disabled.

These were my thoughts until someone told me some time ago that this is
wrong...

1. "man hdparm" says: "-i Display the identification info that
   was obtained from the drive at _boot time_", it doesn't give
   information about the current state of the drive.

2. Try to disable DMA using "hdparm -d0" (you can check it with
   "hdparm -v") - the information displayed by "hdparm -i" won't
   change.

> Tomas Szepe <szepe@pinerecords.com>

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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