[SOLVED] Boot from same mapped drive, regardless of USB drive?

charlweed · 02-01-2010, 03:31 PM

The default Fedora (11 anyway) setup configures the root drive as a mapped logical volume. This is now causing me serious headaches.Here is the grub.conf in question:

title Fedora (2.6.30.10-105.2.4.fc11.i686.PAE)
root (hd0,0)
kernel /vmlinuz-2.6.30.10-105.2.4.fc11.i686.PAE ro root=/dev/mapper/vg_trixter-lv_root quiet
initrd /initrd-2.6.30.10-105.2.4.fc11.i686.PAE.img

The problem is that when I boot with a USB drive attached to a port, my system won't boot. It hangs right after the GRUB screen. This surprises me, because I thought that the volume/partition labels would insure the correct operation of the drive mapper, regardless of the drive order provided by the motherboard after POST.

It's a REALLY long story why I need the USB drive attached, but let's just say I do.

So, is there any way to setup the device mapper to find/configure the correct partitions? Or is there some other solution besides removing the USB drive?

Thanks!

David1357 · 02-01-2010, 05:12 PM

Quote:

Originally Posted by charlweed

Or is there some other solution besides removing the USB drive?

Use a drive label. Read "man e2label".

charlweed · 02-01-2010, 07:02 PM

Quote:

Originally Posted by David1357

Use a drive label. Read "man e2label".

Thanks, but I've spent a few hours trying, and I think e2label is just for filesystems, and that does not seem to help.

Let's say that I labeled my root filesystem
"trixter_root"
and my logical volume root partion is
/dev/mapper/vg_trixter-lv_root

I ran

Code:

e2label /dev/mapper/vg_trixter-lv_root trixter_root

And edited /boot/grub/grub.conf to become

Code:

title Fedora (2.6.30.10-105.2.4.fc11.i686.PAE)
        root (hd0,0)
        kernel /vmlinuz-2.6.30.10-105.2.4.fc11.i686.PAE ro root=LABEL=trixter_root quiet
        initrd /initrd-2.6.30.10-105.2.4.fc11.i686.PAE.img

This still does not work, and I think it's because the LVM itself is breaking, because it's physical volume gets re-ordered when the USB drive is connected at boot time.

If I could identify the physical volume ( currently /dev/sdb2 ) by ID and use that for my logical volume, I think that would be real progress.

I'm wading through the lvm man pages now...

David1357 · 02-02-2010, 09:39 AM

Quote:

Originally Posted by charlweed

If I could identify the physical volume (currently /dev/sdb2) by ID and use that for my logical volume, I think that would be real progress.

ok. What is the output of "fdisk -l" when you boot with and without the USB drive attached?

I poked around a little yesterday. It looks like GRUB2 might have support for accessing file systems by UUID.

But if your volume mapping gets changed by the addition of the USB drive, I do not know how to solve your problem.

charlweed · 02-02-2010, 03:44 PM

If the USB drive is plugged in, it won't boot at all. So I can't run fdisk.

I now think this is some nasty, wicked, EVIL interaction between my kernel
(2.6.30.10-105.2.4.fc11.i686.PAE) and my motherboard (P4C800-E).

GRUB loads, and I have used the grub command line to verify that verify that
root (hd0,0) works
and that grub can "find" /vmlinuz-2.6.30.10-105.2.4.fc11.i686.PAE and /initrd-2.6.30.10-105.2.4.fc11.i686.PAE.img

When I boot from grub, without quiet, the console shows the typical initial log messages before the "Welcome to Fedora" message, but then it hangs. The welcome never shows.
No errors, no nothing.

I've tried a few kernel arguments, nousb, debug, but this is not going anywhere.

David1357 · 02-02-2010, 03:58 PM

Quote:

Originally Posted by charlweed

If the USB drive is plugged in, it won't boot at all. So I can't run fdisk.

Can you boot from a LiveCD or System Rescue CD with the USB drive plugged in and then run "fdisk -l"?

michaelk · 02-02-2010, 04:11 PM

I assume the computer is set to boot off the internal drive first. What is on the USB drive and how is it partitioned? If it contains a LVM partition with the same volume name as the internal drive then this could be the problem.

charlweed · 02-02-2010, 04:20 PM

Quote:

Originally Posted by michaelk

I assume the computer is set to boot off the internal drive first. What is on the USB drive and how is it partitioned? If it contains a LVM partition with the same volume name as the internal drive then this could be the problem.

It's a fat32 with jpegs on it. Please don't ask.

If I plug in the drive after the Fedora welcome message, it boots fine.
In that case, here is the output from blkid

Code:

/dev/sdf1 vfat   garage  (not mounted) BEA2-DC2E

The label is garage, and the UUID is BEA2-DC2E

I'll try a livecd when I burn one.

charlweed · 02-26-2010, 12:27 PM

Once or twice a year, I run into a computer problem that just seems… unreasonable. A case too unusual to anticipate, or diagnose. When I finally find a solution, there is no satisfaction, instead I’m left with just a feeling of sick contempt for the entire world of information technology. This was that kind of problem.

The issue had nothing to do with drive mapping, or boot order. The “hang at boot” problem is only with this particular make-model of USB stick, and only on Linux, and only at the stage where execution is handed to the kernel.

After boot, these USB sticks work fine. Also, I had tested them on other machines, and they had booted fine into Windows and MacOS. I had tried different USB sticks, but they were the same make and model, and failed in the same way. They even hung on booting from a live dvd.
Actually, I don’t know if these sticks are really incompatible with Linux or GRUB, or even if it is some weird interaction with the ASUS P4P800 motherboard. But now I’ve tried several completely different USB sticks, and they have all worked.

We bought these USB sticks in bulk, so I don’t know who the manufacturer is, but the incompatible model is

“Ut 161 USB2FlashStorage USB Device”

USBSTOR\DiskUt161___USB2FlashStorage0.00
USBSTOR\DiskUt161___USB2FlashStorage
USBSTOR\DiskUt161___
USBSTOR\Ut161___USB2FlashStorage0
Ut161___USB2FlashStorage0
USBSTOR\GenDisk
GenDisk