long way is a better learning exercise
 

The reason I didn't mention simply regenerating the initrd from a live CD is that you wouldn't know it was necessary to do so unless you understood what the problem was in the first place.

It is a much better learning exercise to actually have a look inside your initial filesystem especially if you never have before. If you don't know what an initial fs does or what an init script does you need to do this. There are macho users that build initramfs' by hand without a script. There are other cases where at least it is necessary to hand edit the init script such as creating a boot CD for a firewire root drive.

Your problem began as you didn't realize there could be references to your old volume group names inside the initrd filsystem after you had changed fstab and grub.conf. This was most likely as you had never looked inside your initial fs. By doing so you will understand the boot process better and avoid similar problems in the future. I had done this long ago out of curiosity and instantly recognized your problem. Next time you will know immediately.

A hybrid approach is possible. I strongly recommend at least looking at the contents with
cd temp_dir && gzip -dc /boot/initrd-2.6...img | cpio -i -c
and then if you want use the mkinitrd script to fix the references. You should then verify that the corrections were made by looking inside the new initrd.

Sometimes the long way provides more understanding.

Just a note to say I agree with tofino_surfer. Looking at what initrd contains is very interesting and much fun. I also advise you look at it if you don't know what's inside. Look at the init script which is launched by the kernel with nash. You can customize it to your own needs. You can also have a look at the mkinitrd script and see how it is generated

tofino_surfer and agrouf, thank you both for your kind replies.

LVM problems
 

hi everyone,
could some one help me how to rename a volume group.
volume group "volgr1" still has active LVs

and also when i type df -h. It doesn't show any information about my logical volume and volume group