FC6: "mount: could not find filesystem '/dev/root'"

[bthornton]

Hey all,

Getting pretty stumped over this FC6 install... I'm coming off of my #2nd attempt at installing FC6 (x86_64) on my Pentium D 945 system. Both times the installation has gone down without a hitch; however, upon rebooting, I get the following block of error messages:

mount: could not find filesystem '/dev/root'
setuproot: moving /dev failed: No such file or directory
setuproot: error mounting /proc: No such file or directory
setuproot: error mounting /sys: No such file or directory
switchroot: mount failed: No such file or directory
Kernel panic - not syncing: Attempted to kill init!

The installer set the kernel argument for the root fs to "root=LABEL=FedoraRoot", but I have tried changing this to reference the root fs by the "/dev/*" naming convention. No luck.

One observation I have made: I have my root filesystem placed within an LVM logical volume. However, I noticed that after "nash" loads, I don't see any indication that it is searching for LVM volumes. Shouldn't it be searching for VGs/LVs before trying to access a LVM-contained root filesystem?

Any help is greatly appreciated, because this is driving me nuts!

[SlowJet]

Yes, it should point at the lvm and not use labels.

title Fedora Core
root (hd0,0) #<= whatever /boot is on
kernel /vmlinuz-2.6.18-1.2798.fc6 ro root=/dev/VolGroup00/LogVol00 (or 01?) rhgb quiet
inintrd /initrd-2.6.18-1.2798.fc6.img

For some reason your system is using labels. Did you really do a default install and let Anaconda make the partitions?
Did you do anything with /boot or grub differently?

SJ

[bthornton]

Here's the exact entry out of the menu.lst that Anaconda created:

title Fedora Core (2.6.18-1.2798.fc6)
	root (hd0,0)
	kernel /vmlinuz-2.6.18-1.2798.fc6 ro root=LABEL=FedoraRoot rhgb quiet
	initrd /initrd-2.6.18-1.2798.fc6.img

I have tried to boot by editing the kernel line to say both:

kernel /vmlinuz-2.6.18-1.2798.fc6 ro root=/dev/SystemMain/FedoraRoot rhgb quiet

..and...

kernel /vmlinuz-2.6.18-1.2798.fc6 ro root=/dev/mapper/SystemMain-FedoraRoot rhgb quiet

The results are the same both times. This is "default install" in that I made no modifications to the packages that were to be installed. However, since I already have another OS on this machine (Ubuntu) and have a lot of data invested in LVM, I did not grant Anaconda any license to modify the filesystem. I simply have two small (128M) ext3 filesystems for boot partitions (one for each distro) and the rest of the hard drive(s) have simply an LVM partition. I delegated a /boot, root (an LV within LVM), and swap partition to be formatted and used by Anaconda. All of my other partitions are handled by LVM and I didn't even assign them mount points with Anaconda. While I have manually assigned filesystem labels in the past, that shouldn't matter because I had Anaconda format the root filesystem, correct?

I still find it suspicious that there is no indication that LVM is being started before attempting to mount the root filesystem. On my laptop, which I successfully installed FC6 on (from the same media), I see the following line early in the boot process:

Reading all physical volumes.  This may take a while...

..and then it says how many VGs/LVs it found. I see no such output on my desktop that's giving me problems. Am I right to assume that LVM is not being initiated?

Thanks again.

[SlowJet]

I understand what you are saying about your LVM investment,
but placing the /root lv from two different systems on the same VG is not a good idea.
LVM is at a different version as well as the tools.

boot up in rescue mode

vgchange -a y <implied all vg's)
this will make all your vg's available
then do a vgs

If you see vg(s)
then chroot to the img (of fedora
play around and check things out like
mount
mount -a #<= mount everything in fstab
mount
is there a diference, that would be good.

edit /boot/grub/menu.list to be like this (using your boot partition, root vg-lg)

title Fedora Core
root (hd0,0) #<= whatever /boot is on
kernel /vmlinuz-2.6.18-1.2798.fc6 ro root=/dev/VolGroup00/LogVol00 (or 01?) rhgb quiet
inintrd /initrd-2.6.18-1.2798.fc6.img

That's all I know.

SJ

[bthornton]

Thanks for your help, slowjet. I just did the procedure that you said, and I did notice that fstab was still referencing the root filesystem by the label. I changed that to point to the mounted root filesystem, and I also updated /boot/grub/menu.lst to reflect the same filesystem. So both are definitely pointing to the LVM-contained root fs; yet I still get the same problem.

It is as though Anaconda never "realized" that my root filesystem was on an LVM, because there is no indication anywhere that LVM needs to be started/referenced to find the root filesystem. The fact that both grub and fstab are trying to reference the root fs by the "LABEL=" identifier says that something is wrong: It's not possible to find the label of a filesystem in LVM unless the LVM is first started. Yet there is no indication LVM is even trying to start, because I never see the "Reading all physical volumes. [...]" line. In the past, this line was always immediately after "Starting RedHat nash version [blah]"; however, the first line after nash is started is complaining about not being able to find the root filesystem (see original post). Of course it can't find the filesystem: it never started LVM to find it.

Does my reasoning make sense? If so, how would I go about forcing LVM to start when it should?

[bthornton]

Anybody???