Re: [gentoo-user] Grub hangs when a USB disk is attached

[Don Jerman]

I've had problems with disk presentation order changing (fairly
randomly) when USB disks are attached during boot.  Apparently there's
a race between the SCSI controller and the USB controller(s).  If you
attach the USB disk later the SCSI stuff has all been discovered so of
course it gets allocated later in the list, but if it's attached while
booting the USB disk might come first or in the middle somewhere.

This might lead to grub looking for its files in the wrong place,
which might explain the hang.

If you want to test this theory, boot from a CD while the USB is
installed and see where it winds up in /dev, then boot without it.  Be
very careful about assuming drive identities!  That's how I lost my
system disk last time -- /dev/sdb seemed to be partitioned funny and I
figured it out just a little too late.


On 2/28/08, andrea <momesso.andrea@×××××.com> wrote:
> I had no problem booting since last time I partitoned my USB external
> disk.
>
> ==========================================
> Disk /dev/sdc: 80.0 GB, 80026361856 bytes
> 255 heads, 63 sectors/track, 9729 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x00000000
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1               1        2433    19543041   83  Linux
> /dev/sdc2            2434        4866    19543072+  83  Linux
> /dev/sdc3            4867        7299    19543072+  83  Linux
> /dev/sdc4            7300        9729    19518975   83  Linux
> ===========================================
>
> When I boot and the disk is plugged, right after BIOS screen I get a
> "GRUB_" and the boot process hangs.
>
> I guessed it was a BIOS problem so I tried to edit boot order and also
> to disable USB boot (that I don't need).
>
> BTW when the disk is unplugged grub loads perfectly.
>
> Thanks in advance.
>
>
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