Trouble in LVM land

Thu Feb 8 01:12:01 UTC 2007

On Wed, 2007-02-07 at 19:30 -0500, Merv Curley wrote:
> I guess I wasn't clear enough.  The booting procedure reaches the point where 
> udev starts and it first reports
> 
>   /dev/rootvg/rootlv01 clean    xxx  files   xxxx blocks
>   /boot  clean     xxx files   xxxblocks
> 
>   the next group of lines report
> 
> no such device or file  /dev/videovg/videolv01      etc etc 
> 
>    the  videovg group  is just data for mythtv.  The boot procedure stops as 
> usual and there is the usual ' Type Control-D to continue' but when the mtce 
> shell is exited, the computer reboots.
> 
> I have found that the new Ubuntu finds errors with every drive I have on 4 
> systems and I see this error regularly.  Suse 10.2, FC-6, Debian, Mepis, and 
> Kanotix (Debian) never seem to see a problem. I am used to this Control-D 
> message and exiting the shell.
> 
> I can issue no commands,  since booting never finishes.  This has been running 
> just fine, and had rebooted a number of times with no problems.  There are no 
> other distro's on the system which is FC-5 based incidentally.
> 
> I could use a liveCD to look at the drive, 'cept I have no clue what to look 
> for.
> 
> Does that help, or do I just re-install?     Which might be quicker and less 
> edifying.

At the Ctrl-D prompt you should be typing the root user's password and
pressing enter. This will log you into a shell where you will be able to
type commands.

While in this shell you should be able to run commands like:

vgscan
vgdisplay

On some rescue shells you would prefix the command with lvm, e.g.:

lvm vgdisplay

>From the error you mention, "No such device or file", indicates that
device file is not there. This could be because the volume group is not
active or it was misspelled.

Here are the steps that you need to do and before you do them MAKE SURE
YOU KNOW WHICH DEVICES ARE USED FOR FILE SYSTEMS AND WHICH ARE IN VOLUME
GROUPS. These commands may delete data from your disks if you use them
incorrectly.

1. Make sure that the physical devices are visible. Use 'sfdisk -l' to
list disks and partitions. If that's not there try 'fdisk -l'. If you
can see the disks then that's your problem. Check disk connections,
controllers, etc and replace the disk if needed.

2. Ensure that each device is properly setup as an LVM physical volume
(PV). Use 'pvdisplay /dev/hda1', 'pvdisplay /dev/hda2', etc to make sure
each disk looks good.  If pvdisplay gives an error it's possible that a)
a file system was created directly on the partition (like a /boot
partition) or the physical volume was created on the whole disk device
(e.g. hdb instead of hdb1.) NOTE: You almost certanly didn't create a PV
on /dev/hda.

3. Make sure that the volume groups are active. Run 'vgdisplay videovg'.
You should see interesting output. If you don't then the volume group is
not active. If steps 1 and 2 work then this step should work. If you
can't see the VG then try to activate it 'vgchange -a y videovg'.
Alternatively, maybe it was misspelled. Try 'vgdisplay' and see if it is
displayed.

4. The file system may simply need to be checked. I'm going to assume
you are using an ext3 file system. IF YOU AREN'T then don't use this
command. Run 'e2fsck /dev/videovg/videolv01' answer 'y' to all
questions. If you are willing to abandon this file system and re-create.
You could also choose to recreate the LV or even the VG.

5. Finally try to mount the file system. It may be that /etc/fstab has
the wrong file system type listed and refuses to mount it. Run
"mount /dev/videovg/videolv01 /mnt". The command should run without
error and your file system should be mounted on /mnt. Run 'ls /mnt' to
see if you can see your files. Then run 'umount /mnt' to unmount it.

Good luck.
-- 
John Van Ostrand                     Net Direct Inc.
CTO, co-CEO                 564 Weber St. N. Unit 12
                                Waterloo, ON N2L 5C6
john-Da48MpWaEp0CzWx7n4ubxQ at public.gmane.org                   ph: 518-883-1172 x5102
Linux Solutions / IBM Hardware      fx: 519-883-8533

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