Re: Booting a USB hard drive
On Tuesday, May 10, 2011 05:13:46 am Camaleón wrote:
> On Mon, 09 May 2011 13:21:20 -0700, Peter Bonucci wrote:
> > On Monday, May 09, 2011 10:25:44 am Camaleón wrote:
> >> > Booting a USB drive when the drive and computer don't cooperate is an
> >> > old problem. People solved it under Debian years ago. I just don't
> >> > know how they solved it and search engines didn't help.
> >>
> >> There shouldn't be any mistery for this. If the BIOS is capable of
> >> booting from a USB device but the drive where Debian has been installed
> >> is bypassed by the BIOS, I would check that:
> >>
> >> 1/ GRUB is installed into the MBR of the USB disk.
> >
> > I believe I did this while installing Debian on the USB drive. How can
> > I verify it?
>
> Last time I needed to know where was GRUB installed I used:
>
> dd if=/dev/sda bs=512 count=1 | od -a | grep G
>
> (where "sda" is the disk of which MBR is to be queried)
>
> >> 2/ Partition where "/boot" is installed is marked with the bootable
> >> flag (if there is no dedicated partition for "/boot", then "/" should
> >> be the one to be marked).
> >
> > Already done. The "/" directory is marked boot.
>
> Fine. As Arno suggests this is not usually needed but is better to do it,
> just in case.
>
> >> 3/ The system can be properly booted from an external source (i.e.,
> >> using a LiveCD of SuperGrubDisk).
> >
> > The laptop boots from its own hard disk.
>
> Yep, but as GRUB2 is being bypassed, we need to know if there is any
> problem with GRUB2, so we are checking if it's installed in the MBR and
> also if it's properly installed on the partition.
>
> > Under SuperGrubDisk, "List devices/partitions", Grub doesn't see the USB
> > drive. None of the other options boot the drive.
> >
> > Selecting the experimental USB support doesn't seem to change anything.
>
> How is that? It should be accesible by SGD :-?
>
> http://www.supergrubdisk.org/wiki/USB_Boot
>
> But I'm starting to think the problem may be on the Western Digital USB
> drive, as you said you were only facing problems with this concrete USB
> disk... Look, it seems there is one report on WD forums:
>
> How to boot linux from My passport
> http://community.wdc.com/t5/My-Passport-for-PC/How-to-boot-linux-from-My-pa
> ssport/td-p/74214
>
> Greetings,
This is where I am now:
As Larry suggested, I removed the virtual CD from the drive.
I reinstalled Debian on the USB drive.
SuperGrubDisk v1.98s1 does not see the drive, or any of 5 flash drives.
SuperGrubDisk v0.9977 does see the drive.
It reports the drive it as hd1 with a size of 0 K
It does see the 5 flash drives and reports the correct sizes.
file -s /dev/sdb returns:
/dev/sdb: x86 boot sector;
partition 1:
ID=0x83, active, starthead 32, startsector 2048, 488280064 sectors;
partition 2:
ID=0x82, starthead 254, startsector 488282112, 19531776 sectors;
partition 3:
ID=0x7, starthead 254, startsector 507813888, 468889600 sectors,
code offset 0x63
dd if=/dev/sdb ibs=512 count=1 | od -a | grep G returns:
1+0 records in
1+0 records out
512 bytes (512 B) copied, 7.8496e-05 s, 6.5 MB/s
0000260 eot @ bs D del ht D stx G eot dle nul f vt rs \
0000300 | f ht \ bs f vt rs ` | f ht \ ff G D
0000600 G R U B sp nul G e o m nul H a r d sp
Fdisk -l says:
Disk /dev/sdb: 500 GB, 500072348160 bytes
255 heads, 63 sectors/track, 60797 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 * 1 30395 244147806 83 Linux
Warning: Partition 1 does not end on cylinder boundary.
/dev/sdb2 30395 31610 9759487 82 Linux swap
Warning: Partition 2 does not end on cylinder boundary.
/dev/sdb3 31610 60797 234444577 7 HPFS/NTFS
Warning: Partition 3 does not end on cylinder boundary.
The USB Legacy option is enabled in the BIOS.
If grub is in the MBR for the USB drive shouldn't I be able to boot it?
Do you understand what is going on here?
Peter
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