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From: M. Strobel on 6 Dec 2009 16:45
Hi,

I just looked into some Redhat 5.3 and Centos and noticed these address my SATA drive as /dev/hda.

I think this is unusual as I am used for some years now (suse) to see SATA drives driven by the scsi driver
and being called sda.

Is there hard evidence for /dev/sda being better than /dev/hda?

/Str.
From: Lew Pitcher on 6 Dec 2009 21:25
On Dec 6, 4:45 pm, "M. Strobel" <sorry_no_mail_h...(a)nowhere.dee>
wrote:
> Hi,
>
> I just looked into some Redhat 5.3 and Centos and noticed these address my SATA drive as /dev/hda.
>
> I think this is unusual as I am used for some years now (suse) to see SATA drives driven by the scsi driver
> and being called sda.
>
> Is there hard evidence for /dev/sda being better than /dev/hda?

Actually, yes.

The "hd*" devices use the generic IDE comands, while the "sd*" devices
use SCSI commands. SCSI commands can execute in parallel, while IDE
commands don't. This means that "sd*" devices can be more responsive
and "faster" than the corresponding "hd*" devices.

HTH
--
Lew Pitcher
Master Codewright & JOAT-in-training | Registered Linux User #112576
Me: http://pitcher.digitalfreehold.ca/ | Just Linux: http://justlinux.ca/
---------- Slackware - Because I know what I'm doing.
------
From: Van Chocstraw on 7 Dec 2009 08:55
Lew Pitcher wrote:
> On Dec 6, 4:45 pm, "M. Strobel"<sorry_no_mail_h...(a)nowhere.dee>
> wrote:
>> Hi,
>>
>> I just looked into some Redhat 5.3 and Centos and noticed these address my SATA drive as /dev/hda.
>>
>> I think this is unusual as I am used for some years now (suse) to see SATA drives driven by the scsi driver
>> and being called sda.
>>
>> Is there hard evidence for /dev/sda being better than /dev/hda?
>
> Actually, yes.
>
> The "hd*" devices use the generic IDE comands, while the "sd*" devices
> use SCSI commands. SCSI commands can execute in parallel, while IDE
> commands don't. This means that "sd*" devices can be more responsive
> and "faster" than the corresponding "hd*" devices.
>
> HTH
> --
> Lew Pitcher
> Master Codewright& JOAT-in-training | Registered Linux User #112576
> Me: http://pitcher.digitalfreehold.ca/ | Just Linux: http://justlinux.ca/
> ---------- Slackware - Because I know what I'm doing.
> ------


Why would you use SCSI commands on serial ATA? SCSI buses and SCSI
hardrives ARE parallel devices, SATA devices are not.
From: M. Strobel on 7 Dec 2009 15:14
Van Chocstraw schrieb:
> Lew Pitcher wrote:
>> On Dec 6, 4:45 pm, "M. Strobel"<sorry_no_mail_h...(a)nowhere.dee>
>> wrote:
>>> Hi,
>>>
>>> I just looked into some Redhat 5.3 and Centos and noticed these
>>> address my SATA drive as /dev/hda.
>>>
>>> I think this is unusual as I am used for some years now (suse) to see
>>> SATA drives driven by the scsi driver
>>> and being called sda.
>>>
>>> Is there hard evidence for /dev/sda being better than /dev/hda?
>>
>> Actually, yes.
>>
>> The "hd*" devices use the generic IDE comands, while the "sd*" devices
>> use SCSI commands. SCSI commands can execute in parallel, while IDE
>> commands don't. This means that "sd*" devices can be more responsive
>> and "faster" than the corresponding "hd*" devices.
>>
>> HTH
>> --
>> Lew Pitcher
>> Master Codewright& JOAT-in-training | Registered Linux User #112576
>> Me: http://pitcher.digitalfreehold.ca/ | Just Linux: http://justlinux.ca/
>> ---------- Slackware - Because I know what I'm doing.
>> ------
>
>
> Why would you use SCSI commands on serial ATA?

I think SCSI is generic enough to be easily adapted.

> SCSI buses and SCSI
> hardrives ARE parallel devices, SATA devices are not.

Did you not notice? The parallel bus design is no longer state of the art, but rather high speed serial point
to point connection. This is the case with PCI (bus, parallel) vs. PCIe (serial, switched), and also SCSI
Ultra320 (or so) vs. SAS serial attached SCSI.

Same with FibreChannel (serial, switched or loop with point-to-point) vs. ?? - did not exist before.

/Str.
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