unable to boot. cannot find root filesystem

[huckym]

I have been running Kubuntu 7.04 in a vm on XP host (for whatever stupid reasons!) using Vitualbox. I usually keep a snapshot of a stable state and then play around with the vm. Recently I wanted to upgrade to VB 1.5.6 and it said during installation that I wont be able to use old version snapshots. So I wanted to save the snapshot state onto disk and then upgrade.

But after upgrade I am unable to boot kubuntu. It looks for the root file system for a while and then fails to find it, dropping to busybox shell. I looked up some ubuntu forums which said there might be problems due to uuid format and so I changed the boot command to directly specify /dev/sda1 which i know is my root partition. It still doesnt help.

If I use a rescue CD and open a shell on the root partition, I can very well find my home directory and all other data. I checked /etc/mtab and it does show /dev/sda1 mounted as root. but /etc/fstab shows the root partition as mapped to that crazy long uuid. Is that an issue or is that how it is supposed to be?

In any case, I am really hoping that someone would be able to help me out here. I have a lot of stuff installed and losing all that is a big pain.

Also posted on the Virtualbox forum but no help there.

[dibl]

Re: unable to boot. cannot find root filesystem

I would use that rescue CD and take a close look at the /boot/grub/menu.lst file, and see whether anything got changed where it points to the kernel and root partition. It needs to match what is set in the /etc/fstab file.

Booting by UUID was kind of the new thing in Edgy and Feisty, and there are lots of more experienced users who still don't care for it. But, with the advent of removable storage media like USB sticks and drives, it became necessary to upgrade the old Unix device designation system. Personally I'm happy with it -- it's very reliable, except if you fiddle with your partitions and don't remember that they can get re-designated with new UUIDs. So I recommend you stick with using the UUID to designate the partition where the kernel and root filesystem are. But upgrading VB should not have changed that.

That's all I can offer.

I just got home from helping a family friend recover valuable data from a trashed and crashed Windows system. These things happen .... to everyone.

[MoonRise]

Re: unable to boot. cannot find root filesystem

I use VB and I do remember reading that if you move a virtual disk or upgrade there are procedures to follow as it does effect the UUID of the virtual disk. I don't remember where I read it, must have been on their web site.


Edit: Found this. Very conflicting post at VB, but maybe it will help.

http://forums.virtualbox.org/viewtopic.php?p=9916

[huckym]

Re: unable to boot. cannot find root filesystem

I tried creating a clone and then a new virtual machine using that vdi but to no avail. Thanks for the suggestion though.

[MoonRise]

Re: unable to boot. cannot find root filesystem

Did that clone give any indication of what the UUID might have been? You could probably mount a LiveCD iso image in your virtual machine and check the UUID for that virtual disk and make sure that is what is used in GRUB for that virtual machine/virtual disk combo.

[huckym]

Re: unable to boot. cannot find root filesystem

ok so this is what i have now.

/etc/fstab and grub entry has the following uuid:
d80c3cfb-5890-4498-a65c-272d64b87c2f

and the hard disk uuid that i see in the virtualbox xml files is
97d97ab1-009d-4bdc-b783-4782618821ac

I tried changing the /etc/fstab and grub entry to match the xml file entry but that did not help. I got an error during boot saying
/dev/disk/by-uuid/97d97ab1-009d-4bdc-b783-4782618821ac does not exist.
I checked in the /dev/disk/by-uuid dir and it had the old entry.
I tried creating a new link to the root dir /dev/sda1 with the new uuid but same error as before and the next time i looked there, the new link had disappeared. I guess I cant add it manually that way.

I also tried changing the xml file entry to match the other but then when i launch the virtual machine it says that the actual uuid does not match the registered entry.

so in short, the uuid's are different and I dont know how to get them to match.