[CentOS] install detecting disk as sdb not sda

wwp subscript at free.fr
Fri Feb 3 22:02:52 UTC 2012


Hello Ross,


On Fri, 3 Feb 2012 16:01:53 -0500 Ross Walker <rswwalker at gmail.com> wrote:

> On Feb 3, 2012, at 1:34 PM, wwp <subscript at free.fr> wrote:
> 
> > Hello Jerry,
> > 
> > 
> > On Fri, 03 Feb 2012 12:24:14 -0500 Jerry Geis <geisj at pagestation.com> wrote:
> > 
> >> I am trying to install 6.2 on a machine.
> >> I am using PXE as I have done so a number of times.
> >> 
> >> My hard disk is being detected as sdb and not sda.
> >> My kickstart config is wanting it at sda.
> >> 
> >> There are no other disks in the unit. It has and SD slot and an esata
> >> although BIOS does not appear to have a disable for either of those devices.
> >> 
> >> Is there anyway to "force" the disk to sda ?
> >> or find out what its detecting at sda and disable that from the PXE boot 
> >> line?
> >> 
> >> Doing " dmesg | grep sda" does say SCSI removable disk.
> >> 
> >> So how can I tell linux to NOT include that when installing?
> > 
> > I noticed that behaviour with my CentOS6 (installed and kept up-to-date
> > using yum). This happened since kernel kernel-2.6.32-220.el6.x86_64 and
> > furthers updates. Was working as expected (my laptop's hdd mounted as
> > sda) with previous kernels, up to kernel-2.6.32-131.21.1.el6.x86_64.
> > 
> > I wonder if that behaviour, and the *change* of behaviour is an issue
> > that should be reported, and how to handle it on installed systems!
> > For now, I'm either booting w/ no USB disk plugged, or booting
> > a 2.6.32-131 kernel.
> 
> You can try disabling USB disk support in the bios.

Right, but I can't make such settings permanent, as I need to boot from
a USB disk from time to time, thus, entering BIOS and changing settings
costs more than unplugging stuff :-).

An aspect of the problem w/ that behaviour change introduced w/ recent
kernel updates, is that some mount mapping tables (fstab for instance)
are broken if they rely on mount order (sda, hda, etc.) instead of
device ID or label.


Regards,

-- 
wwp
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