Re: Possibly erroneous "device not present" message during boot
On Wed 19 Apr 2017 at 20:25:46 (+0200), Pascal Hambourg wrote:
> Le 19/04/2017 à 09:46, GiaThnYgeia a écrit :
> >
> >Question: You have a system with everything on a HD /dev/sda, you use
> >/dev/sdb a live disk to boot and install debian on /dev/sdc including
> >the grub on /dev/sdc
> >You unplug the live disk and reboot, what will grub do by default, what
> >systems will it show, by default?
>
> It depends which GRUB boots.
>
> If it's the GRUB on the hard disk that was /dev/sda during the
> installation, it will show the same systems as before the
> installation, i.e. it won't show the new system until you run
> update-grub to update its menu.
>
> If it's the GRUB on the device that was sdc during the installation,
> it will show all present systems that os-prober can detect.
>
> >I did not specify whether there is grub installed on /dev/sda or not, so
> >there are two variations.
>
> Indeed.
>
> >I suspect based on Bios settings the system
> >will either go to hd or to usb to boot,
>
> You did not mention previously that /dev/sdc was a USB device.
>
> >and that will be sda
>
> The boot order in the BIOS has no effect on the device discovery and
> naming in the Linux system. Also, most of the times USB devices lose
> the discovery race against ATA devices due to extra delay. So hda
> will probably always be the hard disk regardless of the boot device.
I've seen just one instance reported where an externally connected
USB drive got /dev/sda whereas the internal mSATA got /dev/sdb.
This was from someone who was about to dd copy the drive (which is
why they checked).
Cheers,
David.
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