Ubuntu - disk management behaviour

Goh Lip g.lip at gmx.com
Thu Jul 21 17:57:24 UTC 2011

On Fri, 22 Jul 2011 01:41:21 +0800, Daniele Guerrieri  
<d.guerrieri at gmail.com> wrote:

> Hi people,
> have you ever noticed strange behaviours with grub2 and usb key?
> I've got an acer ao5320h netbook, and
> If, for example, the scsi disk is on /dev/sda, and root partition in
> /dev/sda7, when i plug in a usb key the key is under /dev/sdb.
> But if i boot from usb, the usb key becomes /dev/sda, and the first
> disk becomes /dev/sdb.
> So grub2, in which disk references are made of /dev/sd[xn] ,behaves  
> weirdly.
> So, does ubuntu rely on UUID or /dev/sdxn?
> Thanks,
> Daniele

Yes, that's how it is, but that is due to the bios rather than grub and  
that's why the grub2 menu entries always use uuid so the boot is always  
correct (unless you manually modify it to /dev/sdxy and (hdx,y), which you  
shouldn't). But if want to manually modify, use uuid or label.

And by the way, it has always been like that way before grub2, which  
necessitates the need to manually modify to boot correctly (before grub2).

Regards - Goh Lip

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