[gentoo-user] OT: How does kernel determine drive order?

[gentoo-user] OT: How does kernel determine drive order?

[Anthony E. Caudel]

How does the kernel (2.6.22) determine the order of SATA drives (sda,
sdb, etc.) when it boots up?

Tony

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Re: [gentoo-user] OT: How does kernel determine drive order?

[Jarry]

Anthony E. Caudel wrote:
> How does the kernel (2.6.22) determine the order of SATA drives (sda,
> sdb, etc.) when it boots up?

I just checked my computer, and sda is the drive plugged in
the first sata-port, and sdb the one in the second port
(according to the info in motherboard manual).

Maybe it is something similar as with p-ata drives, where hda
is always the master drive on the first pata channel...

Jarry
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Re: [gentoo-user] OT: How does kernel determine drive order?

[Stroller]

On 5 Nov 2007, at 05:17, Jarry wrote:

> Anthony E. Caudel wrote:
>> How does the kernel (2.6.22) determine the order of SATA drives (sda,
>> sdb, etc.) when it boots up?
>
> I just checked my computer, and sda is the drive plugged in
> the first sata-port, and sdb the one in the second port
> (according to the info in motherboard manual).
>
> Maybe it is something similar as with p-ata drives, where hda
> is always the master drive on the first pata channel...

What he said.

But if you're having a problem with it, or want to change the driver  
order, then take a poke around in /etc/udev/rules.d/.

Stroller.
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Re: [gentoo-user] OT: How does kernel determine drive order?

[Anthony E. Caudel]

Jarry wrote:
> Anthony E. Caudel wrote:
>> How does the kernel (2.6.22) determine the order of SATA drives (sda,
>> sdb, etc.) when it boots up?
>
> I just checked my computer, and sda is the drive plugged in
> the first sata-port, and sdb the one in the second port
> (according to the info in motherboard manual).
>
> Maybe it is something similar as with p-ata drives, where hda
> is always the master drive on the first pata channel...
>
> Jarry
For my mobo (Asus A8N-SLI Premium), sda is plugged into SATA slot 3. 
Interestingly, it is NOT the first drive listed in the BIOS either.

I think, but not sure, that the kernel looks at the buses to determine
the drive order.

Maybe someone can confirm?

Tony

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Re: [gentoo-user] OT: How does kernel determine drive order?

[Anthony E. Caudel]

Stroller wrote:
>
> On 5 Nov 2007, at 05:17, Jarry wrote:
>
>> Anthony E. Caudel wrote:
>>> How does the kernel (2.6.22) determine the order of SATA drives (sda,
>>> sdb, etc.) when it boots up?
>>
>> I just checked my computer, and sda is the drive plugged in
>> the first sata-port, and sdb the one in the second port
>> (according to the info in motherboard manual).
>>
>> Maybe it is something similar as with p-ata drives, where hda
>> is always the master drive on the first pata channel...
>
> What he said.
>
> But if you're having a problem with it, or want to change the driver
> order, then take a poke around in /etc/udev/rules.d/.
>
> Stroller.
But would this be relevant?  The kernel boot order is set at boot time,
long before udev comes up.

Tony

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Re: [gentoo-user] OT: How does kernel determine drive order?

[Albert Hopkins]

On Mon, 2007-11-05 at 11:43 -0600, Anthony E. Caudel wrote:
> Jarry wrote:
> > Anthony E. Caudel wrote:
> >> How does the kernel (2.6.22) determine the order of SATA drives (sda,
> >> sdb, etc.) when it boots up?
> >
> > I just checked my computer, and sda is the drive plugged in
> > the first sata-port, and sdb the one in the second port
> > (according to the info in motherboard manual).
> >
> > Maybe it is something similar as with p-ata drives, where hda
> > is always the master drive on the first pata channel...
> >
> > Jarry
> For my mobo (Asus A8N-SLI Premium), sda is plugged into SATA slot 3. 
> Interestingly, it is NOT the first drive listed in the BIOS either.
> 
> I think, but not sure, that the kernel looks at the buses to determine
> the drive order.
> 
> Maybe someone can confirm?

>From what I've heard/read, you cannot guarantee device ordering of
SCSI(-like) devices.  It's recommended that you use disk labels/UUIDs
(and initramfs/initrd for / device).

My BIOS actually lets you select with drives show up in the BIOS as well
as what order.  On one machine I have 8 drives but only 1 configured in
the BIOS (the boot drive).  However at the Linux level it shows up
as /dev/sdj or something like that.  But I think if I had a usb stick in
plugged in while it's being booted it might show up as something
different.

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Re: [gentoo-user] OT: How does kernel determine drive order?

[Stroller]

On 5 Nov 2007, at 17:45, Anthony E. Caudel wrote:
>>>>
>>>> How does the kernel (2.6.22) determine the order of SATA drives  
>>>> (sda,
>>>> sdb, etc.) when it boots up?
>> ...
>> But if you're having a problem with it, or want to change the driver
>> order, then take a poke around in /etc/udev/rules.d/.
>
> But would this be relevant?  The kernel boot order is set at boot  
> time,
> long before udev comes up.

Doh! Good point. I assume you're right.

Stroller.
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