[gentoo-user] [OT] ESATA drive changes the root device -- how to deal with it?

[gentoo-user] [OT] ESATA drive changes the root device -- how to deal with it?

[walt]

Okay, my root partition is on /dev/sda (normally), which is a sata
drive connected to the onboard sata controller.

The problem is that I also have a plug-in ESATA docking station, which
is not always powered on.  When it *is* powered on, my kernel names the
disk /dev/sda, and that forces the root device to be named /dev/sdb
instead of sda.  Crashing ensues during bootup.

The machine's BIOS doesn't even recognize the ESATA controller, so
I can't fiddle with anything there.

Anyone have any ideas how to get a kernel to mount the root partition
based on the pci slot number or something equivalent?

I've tried using a disk label in fstab instead of a device name, but the
problem is that the kernel mounts the wrong partition before it has a
chance to read fstab.

I've also tried using rdev to set the root device to the disk's major
and minor numbers but that fails because the kernel switches the minor
device numbers along with the device names.

Any clues would be much appreciated.

Re: [gentoo-user] [OT] ESATA drive changes the root device -- how to deal with it?

[Volker Armin Hemmann]

On Donnerstag 11 Juni 2009, walt wrote:
> Okay, my root partition is on /dev/sda (normally), which is a sata
> drive connected to the onboard sata controller.
>
> The problem is that I also have a plug-in ESATA docking station, which
> is not always powered on.  When it *is* powered on, my kernel names the
> disk /dev/sda, and that forces the root device to be named /dev/sdb
> instead of sda.  Crashing ensues during bootup.
>
> The machine's BIOS doesn't even recognize the ESATA controller, so
> I can't fiddle with anything there.
>
> Anyone have any ideas how to get a kernel to mount the root partition
> based on the pci slot number or something equivalent?
>
> I've tried using a disk label in fstab instead of a device name, but the
> problem is that the kernel mounts the wrong partition before it has a
> chance to read fstab.
>
> I've also tried using rdev to set the root device to the disk's major
> and minor numbers but that fails because the kernel switches the minor
> device numbers along with the device names.
>
> Any clues would be much appreciated.

afaik you can use labels in grub too.

Re: [gentoo-user] [OT] ESATA drive changes the root device -- how to deal with it?

[Stroller]

On 11 Jun 2009, at 16:37, Volker Armin Hemmann wrote:
> On Donnerstag 11 Juni 2009, walt wrote:
>> ...
>> The problem is that I also have a plug-in ESATA docking station,  
>> which
>> is not always powered on.  When it *is* powered on, my kernel names  
>> the
>> disk /dev/sda, and that forces the root device to be named /dev/sdb
>> instead of sda.  Crashing ensues during bootup.
>> ...
>> I've tried using a disk label in fstab instead of a device name,  
>> but the
>> problem is that the kernel mounts the wrong partition before it has a
>> chance to read fstab.
>> ...
> afaik you can use labels in grubtoo.

I believe  you need an initrd/initramfs in order to do so.

See Neil Bothwick's first post:
http://www.mail-archive.com/gentoo-user@lists.gentoo.org/msg81584.html

Stroller.

[gentoo-user] Re: [OT] ESATA drive changes the root device -- how to deal with it?

[walt]

Stroller wrote:
>
> On 11 Jun 2009, at 16:37, Volker Armin Hemmann wrote:
>> On Donnerstag 11 Juni 2009, walt wrote:
>>> ...
>>> The problem is that I also have a plug-in ESATA docking station, which
>>> is not always powered on. When it *is* powered on, my kernel names the
>>> disk /dev/sda, and that forces the root device to be named /dev/sdb
>>> instead of sda. Crashing ensues during bootup.
>>> ...
>>> I've tried using a disk label in fstab instead of a device name, but the
>>> problem is that the kernel mounts the wrong partition before it has a
>>> chance to read fstab.
>>> ...
>> afaik you can use labels in grubtoo.
>
> I believe you need an initrd/initramfs in order to do so.
>
> See Neil Bothwick's first post:
> http://www.mail-archive.com/gentoo-user@lists.gentoo.org/msg81584.html

That's a very interesting link, thanks.

Re: [gentoo-user] [OT] ESATA drive changes the root device -- how to deal with it?

[Dirk Heinrichs]

[-- Attachment #1: Type: text/plain, Size: 371 bytes --]

Am Donnerstag 11 Juni 2009 17:32:18 schrieb walt:
> I've tried using a disk label in fstab instead of a device name, but the
> problem is that the kernel mounts the wrong partition before it has a
> chance to read fstab.

fstab is the wrong place. It should be on the kernel command line (that thing 
you configure in your bootloader's config).

HTH...

	Dirk

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 190 bytes --]

[gentoo-user] Re: [OT] ESATA drive changes the root device -- how to deal with it?

[walt]

walt wrote:
> Okay, my root partition is on /dev/sda (normally), which is a sata
> drive connected to the onboard sata controller.
>
> The problem is that I also have a plug-in ESATA docking station, which
> is not always powered on. When it *is* powered on, my kernel names the
> disk /dev/sda, and that forces the root device to be named /dev/sdb
> instead of sda. Crashing ensues during bootup...

Here's an interesting factoid -- somewhere between kernel 2.6.28 and
2.6.30, the system for naming scsi disks changed.  All I did was use
a newer kernel and the reversing device names went away.