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From: zaman on 20 May 2010 06:04
On May 19, 9:03 pm, Pascal Hambourg <boite-a-s...(a)plouf.fr.eu.org>
wrote:
> zaman a écrit :
>
> > On May 18, 7:16 pm, Pascal Hambourg <boite-a-s...(a)plouf.fr.eu.org>
> > wrote:
>
> >> zaman a écrit :
>
> >>>    I want to know enable 32-bit IO-support on my SATA hard drive
> >>> using hdparm . But before I enable 32-bit support , I want to know
> >>> whether my hard drive supports 32-bit IO or not.
>
> >> 32-bit support is not related to the drive but to the host adapter.
> >> Besides, it is relevant only for IDE (parallel ATA) PIO modes, not for
> >> (U)DMA modes nor SATA. In short, you don't need to care about that.
>
> > The manual page of hdparm says "get/set SATA/IDE device parameters" .
>
> The manual page also says "-c  Query/enable (E)IDE 32-bit I/O support".
> (E)IDE (i.e. parallel ATA) only, not SATA.
>
> > So , the tuning applies to SATA drive also
>
> Not all settings apply to all kinds of host adapter/disk. PIO and DMA
> mode settings are also specific to parallel ATA.
>
> There is only one situation where 32-bit support would apply to a SATA
> disk, when the SATA host adapter is in legacy IDE compatibility mode and
> DMA is disabled (-d0) so PIO is used. But you don't want to be in such a
> situation, because performance would probably be awful.

Thanks for the clarification . I can see also see the following in one
of our host .

====
$ dmesg | grep -i sata
ata1: SATA max UDMA/133 cmd 0x30C0 ctl 0x30B6 bmdma 0x30A0 irq 193
ata2: SATA max UDMA/133 cmd 0x30B8 ctl 0x30B2 bmdma 0x30A8 irq 193

$ sudo hdparm /dev/sda

/dev/sda:
HDIO_GET_MULTCOUNT failed: Inappropriate ioctl for device
IO_support = 0 (default 16-bit)
readonly = 0 (off)
readahead = 256 (on)
geometry = 30401/255/63, sectors = 250059350016, start = 0
===

from dmesg output , looks like the drive is a SATA hard drive . So ,
setting to 32-bit IO probably will not make sense for this disk ? .
Also , what the above error signifies (HDIO_GET_MULTCOUNT) . ?

Thanks
Zaman
From: Pascal Hambourg on 20 May 2010 07:19
zaman a �crit :
>
> /dev/sda:
> HDIO_GET_MULTCOUNT failed: Inappropriate ioctl for device
> IO_support = 0 (default 16-bit)
> readonly = 0 (off)
> readahead = 256 (on)
> geometry = 30401/255/63, sectors = 250059350016, start = 0
> ===
>
> from dmesg output , looks like the drive is a SATA hard drive . So ,
> setting to 32-bit IO probably will not make sense for this disk ? .

Probably not.

> Also , what the above error signifies (HDIO_GET_MULTCOUNT) . ?

Multiple sector count (hdparm -m), like 32-bit I/O support, is specific
to IDE operating in PIO mode, so I guess it is disabled in the SATA
driver. Don't ask me why the 32-bit I/O support is not disabled too.
From: zaman on 21 May 2010 00:43
On May 20, 4:19 pm, Pascal Hambourg <boite-a-s...(a)plouf.fr.eu.org>
wrote:
> zaman a écrit :
>
>
>
> > /dev/sda:
> >  HDIO_GET_MULTCOUNT failed: Inappropriate ioctl for device
> >  IO_support   =  0 (default 16-bit)
> >  readonly     =  0 (off)
> >  readahead    = 256 (on)
> >  geometry     = 30401/255/63, sectors = 250059350016, start = 0
> > ===
>
> > from dmesg output , looks like the  drive is a  SATA hard drive . So ,
> > setting to 32-bit IO probably will not make sense for this disk ?  .
>
> Probably not.
>

So , what about the performance of the disk since it is set to16-bit
and we can't change it to 32-bit as it is a SATA hard drive .
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