Unable to boot RHEL 5.2 and Unable to mount root file system in rescue mode

vknemannavar · 01-28-2010, 01:33 AM

Environment:
A 32-bit kernel RHEL5.3 system running on a virtual machine. The root(/) filesystem is on an LV.

Issue:
Unable to resize the FS after extending the root LV since it is mounted. After extending the LV, online resizing of the FS was not supported and the root filesystem could not be unmounted while it was in use. On rebooting, I got a kernel panic error. In runlevel 1, I couldn't run chroot, couldn't find the /etc/fstab, root FS could not be mounted, fsck did not run (tried block 31 for second copy of superblock using dd count=1 bs=4k skip=31 seek=1 if=/dev/sda2 of=/dev/sda2), couldn't find any rpm on installation media to install unix-utils rpm. On running commands in runlevel 1, I got the following output. Please advise.

chroot /mnt/sysimage/
chroot:cannot run command '/bash/sh': No such file or directory

fdisk -l
Disk /dev/sda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 1305 10377990 8e Linux LVM

fsck -p /dev/sda2
fsck 1.39 (29-May-2006)
WARNING: couldn't open /etc/fstab: No such file or directory
e2fck 1.39 (29-May-2006)
Couldn't find ext2 superblock, trying backup blocks...
fsck.ext2: Bad magic nimber in super-block while trying to open /dev/sda2

DrLove73 · 01-28-2010, 05:14 AM

Hi, welcome to the LQ forums.

Your problem is that when you boot like that your lvm volumes are not recognized and mounted. You need to mount them first with:

Code:

lvm pvscanv

Code:

lvm vgscan

Code:

lvm vgchange VolGroup00 -a y

(If your Volume Group has that name, or change it to match the output of the previous command

Code:

lvm lvscan

If lvm does not work, you need to boot from Installation media with "linux rescue". DVD or what ever. LVM volumes should be mounted automatically when rescue searches for existing installations.

Now you can use

Code:

fsck -p /dev/VolGroup00/LogVol00

or what ever partition you need to check.

If you boot from Installation media, you can mount partitions with:

Code:

mount /dev/VolGroup00/LogVol?? /mnt/sysimage

, etc

DrLove73 · 01-28-2010, 05:35 AM

The way I resize(d) LVM partition is following:

Boot from Installation media, let it find and mount partitions (or avoid searching for them and use above post until mounting segment).
then

Code:

lvm vgdisplay VolGroup00

to see LVM related data.
Now unmount LVM partitions like this:

Code:

umount /mnt/sysimage/boot

and

Code:

umount /mnt/sysimage

,
order LVM do deactivate partitions from that volume group:

Code:

lvm lvchange -a n /dev/VolGroup00/LogVol00 /dev/VolGroup00/LogVol00

(add more at the end if you have more inside that volume group), then resize phisical volume is necesary. I used following syntax for single drive (on the RAID):

Code:

lvm pvresize -v -d /dev/md3

, you use your correct disk instead of "/dev/md3".

Then activate volume groups again:

Code:

lvm vgchange -ay

and activate LV's with

Code:

lvm lvscan

Then read volume group to see the Free PE size:

Code:

lvm vgdisplay VolGroup00

, and resize the LV you want (in this case for another 3GB):

Code:

lvm lvresize -L +3GB /dev/VolGroup00/LogVol00

OR to use number of entities use

Code:

lvm lvresize -l +<number> /dev/VolGroup00/LogVol00

this last syntax I have not tested!.

Now see what you have done with

Code:

lvm lvdisplay /dev/VolGroup00/LogVol00

and

Code:

df -kh

, then fix partition with

Code:

umount /dev/VolGroup00/LogVol00

Code:

resize2fs -p /dev/VolGroup00/LogVol00

THIS MAY BE REDUNANT:

Code:

e2fsck -f /dev/VolGroup00/LogVol00

That should be it.

vknemannavar · 01-28-2010, 11:33 PM

Quote:

Originally Posted by DrLove73

The way I resize(d) LVM partition is following:

Boot from Installation media, let it find and mount partitions (or avoid searching for them and use above post until mounting segment).
then

Code:

lvm vgdisplay VolGroup00

to see LVM related data.
Now unmount LVM partitions like this:

Code:

umount /mnt/sysimage/boot

and

Code:

umount /mnt/sysimage

,
order LVM do deactivate partitions from that volume group:

Code:

lvm lvchange -a n /dev/VolGroup00/LogVol00 /dev/VolGroup00/LogVol00

(add more at the end if you have more inside that volume group), then resize phisical volume is necesary. I used following syntax for single drive (on the RAID):

Code:

lvm pvresize -v -d /dev/md3

, you use your correct disk instead of "/dev/md3".

Then activate volume groups again:

Code:

lvm vgchange -ay

and activate LV's with

Code:

lvm lvscan

Then read volume group to see the Free PE size:

Code:

lvm vgdisplay VolGroup00

, and resize the LV you want (in this case for another 3GB):

Code:

lvm lvresize -L +3GB /dev/VolGroup00/LogVol00

OR to use number of entities use

Code:

lvm lvresize -l +<number> /dev/VolGroup00/LogVol00

this last syntax I have not tested!.

Now see what you have done with

Code:

lvm lvdisplay /dev/VolGroup00/LogVol00

and

Code:

df -kh

, then fix partition with

Code:

umount /dev/VolGroup00/LogVol00

Code:

resize2fs -p /dev/VolGroup00/LogVol00

THIS MAY BE REDUNANT:

Code:

e2fsck -f /dev/VolGroup00/LogVol00

That should be it.

I have tried all the option, I am not finding the Volume group itself

vknemannavar · 01-28-2010, 11:39 PM

I have tried all the above mentioned options, but i am not finding volume group itself

DrLove73 · 01-29-2010, 09:05 AM

If you can not find any volume group (VolGroup00 is just a default name), then it seams you have messed up your LVM partition. I have never had this problem, so somone else will have to step in.