Re: Question about scsi device names

[walt <w41ter@gmail.com>]

Billy Crook wrote:
> ... the letter naming of block
> devices in /dev/ is arbitrary and should be presumed unreliable.  It
> is dependant on the order in which the devices were detected.  In your
> case, it is likely that modules are being loaded in another order than
> before.  This could happen for a variety of reasons including module
> renames, removals, or additions.
>
> To reliably reference block devices, use LABEL=, or UUID= in fstab, or
> /dev/disk/by-*/* anywhere else...

Thanks, that's helpful info.  The reason this came up is that the sata
disk on the onboard controller is the boot disk, and it's annoying to
have the boot fail because the ESATA disk is powered on or off, as the
case may be.

The kernel chooses the root partition based on its own value of rdev,
I believe, and that's what I'm trying to set properly.  I've been trying
various different combos of the label and /dev/disk/foo/bar but in the
end rdev just winds up being /dev/sda or /dev/sdb, regardless of what I
type.

Do you know of any way to get around this problem?

Thanks!


> On Thu, Jun 11, 2009 at 19:36, walt<w41ter@gmail.com>  wrote:

>> I have a machine with two sata disks, one connected to the
>> onboard sata controller, the other to an add-on ESATA board
>> plugged into the PCIX slot.
>>
>> When I boot a kernel from the 2.6.28 series, the onboard
>> controller's disk gets dubbed /dev/sdb, and the ESATA disk
>> is /dev/sda.
>>
>> When I boot the same machine with a more recent kernel like
>> Linus's 2.6.30 series, the device names are reversed...