ThorinO
asked on
Alert! /dev/mapper/hostname-root does not exit. Dropping to a shell! (Ubuntu, LVM) Won't boot
I have an Ubuntu x64 server that I came in to find not working. I recently did a V2V of it but it was working after the move then started doing this.
I pressed "c" from the Grub menu and did set and LS to get some information. I also did "e" to try a change but to no avail. Kinda know what is going on but not sure how to resolve.
I pressed "c" from the Grub menu and did set and LS to get some information. I also did "e" to try a change but to no avail. Kinda know what is going on but not sure how to resolve.
Personally, I do not use Grub. But faced with this kind of problem, I would boot off a USB stick or CD, mount the regular root disk read/write, and chroot to it. Then I would at least mount /proc or maybe mount -a. Then I would get the boot loader (LILO in my case) to reinstall itself to the boot sector.
Try this:
grub> setup (hd0)
grup> quit
grub> setup (hd0)
grup> quit
try and modify the kernel line to read the following for the root entry;
root=/dev/mapper/mon-01-ro ot
root=/dev/mapper/mon-01-ro
ASKER
Duncan, would you be able to provide the commands to complete that?
farzanj: it says setup is an unknown command
jools: I changed it to "linux /vmlinuz-2.6.35-28-server root=/dev/mapper/<serverna me>-root" and removed the ro /quiet. It started to boot so I thought I was good to go but dropped to the shell again with the same error message.
farzanj: it says setup is an unknown command
jools: I changed it to "linux /vmlinuz-2.6.35-28-server root=/dev/mapper/<serverna
Can you list the devices in /dev/mapper or just specify /dev/<volumegroup>/<root-l ogicalvolu mename>
I've not seen <servername>-root used before but that doesnt mean it cant be setup that way.
I've not seen <servername>-root used before but that doesnt mean it cant be setup that way.
btw, you can leave "ro quiet" in there if you like.
ASKER
I'm not sure why it is setup the way it is, I let the Ubuntu installation configure LVM. I don't even know why it broke yet either =\
ASKER
The LVM name looks correct other than it added additional hypens in there for some reason.
So for exmple my system is called company-mon-01 and it changed it to company--mon--01 and when I change it to a single - it still does not work.
So for exmple my system is called company-mon-01 and it changed it to company--mon--01 and when I change it to a single - it still does not work.
Boot off bootable USB stick or install CD. Get a command prompt: if using the install CD and it goes straight to a GUI you may have to try Ctr-Alt-F2 (function key 2) or other function keys in range 1 - 6.
When you get a command prompt, mount your normal root disk. To do this you may need to modprobe the relevant file system E.g.
mkdir /tmproot
mount /dev/whatever /tmproot
Post back when you can get that far
When you get a command prompt, mount your normal root disk. To do this you may need to modprobe the relevant file system E.g.
mkdir /tmproot
mount /dev/whatever /tmproot
Post back when you can get that far
Alsobe careful of the difference between underscore and minus when renaming
ASKER
I downloaded and booted into an Ubuntu LiveCD and have a terminal open. I'm not sure what to do with the modprobe command you suggested.
I guess were still dealing with the /dev/mapper/<whatever> doesnt exist?
Does the file exist? It should be the LV for root on your system.
Unfortunately if you cant find out you will need to use the ubuntu live cd to have a look, does the live cd find the volume groups and enable them?
If it does you can mount the filesystem locally under the live cd and have a look, if it doesnt you may need to scan for the volumes and activate the volume group.
eg/
# vgscan
# vgchange -a y <volumegroupname>
Does the file exist? It should be the LV for root on your system.
Unfortunately if you cant find out you will need to use the ubuntu live cd to have a look, does the live cd find the volume groups and enable them?
If it does you can mount the filesystem locally under the live cd and have a look, if it doesnt you may need to scan for the volumes and activate the volume group.
eg/
# vgscan
# vgchange -a y <volumegroupname>
You may not have to do a modprobe. You should be able to cat /proc/partitions to see what's available. Maybe the LiveCD has already mounted your disks - try mount to show what is mounted. cat /proc/filesystems to see what file systems are supported by the currently loaded modules.
If your disks have been mounted read-only, it may be prudent to run fsck -n on them before making the writable (by mount -oremount,rw disk_name)
If your disks have been mounted read-only, it may be prudent to run fsck -n on them before making the writable (by mount -oremount,rw disk_name)
ASKER
vgscan did not show anything
cat /proc/partitions has a loop0 listed
Starting to get worried my data is gone :(
cat /proc/partitions has a loop0 listed
Starting to get worried my data is gone :(
ASKER
No other drives are mounted either.
vgscan should have picked up some LVM's if they were there, can you post fdisk -l.
Also, whats a v2v and what happened after the v2v and before it just stopped working? Any updates? Hardware changes?
Also, whats a v2v and what happened after the v2v and before it just stopped working? Any updates? Hardware changes?
You can also try
lvmdiskscan
For seeing all the block devices on the system issue this command
lshal | grep 'block.device'
lvmdiskscan
For seeing all the block devices on the system issue this command
lshal | grep 'block.device'
ASKER
lvmdiskscan found ram0-15 and loop0
There are 3 block devices found
/dev/fd0 and /dev/sr0
I did a VMware conversion (virtual to virtual) and all was well and then for some reason poof it was broken. Of course I had a backup of the system until the other day when I deleted them...
There are 3 block devices found
/dev/fd0 and /dev/sr0
I did a VMware conversion (virtual to virtual) and all was well and then for some reason poof it was broken. Of course I had a backup of the system until the other day when I deleted them...
what about fdisk -l?
What disks are configured in the VM?
What disks are configured in the VM?
Looks pretty bad to me. Sorry I have no further advice.
ASKER
fdisk -l shows nothing. The VM only has 1 VMDK on it. I am thinking that maybe I attach the VMDK to another VM (Linux or Windows) and see if I can mount and read it
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ASKER
My solution was the resolution but help was provided.