I've got two systems. On one, I decided to try and increase the virtual disk /dev/sda. So I delete the partition using fdisk and recreate it with a larger end size but identical start location. ( Initially, I make the mistake of creating the partition as an extended one then revert to making it a primary one. ) I also ensure the type (id) is set to 8e ( Linux LVM ).
I write the new partition to disk, reboot and run into a boot issue.
And now the disk won't mount. So I try to recreate the initramfs using the following:
Recovery Option 3 (shell):
vgscan -v --mknodes
vgchange -a y
mount /dev/mapper/centos-root /mnt/root
mount -o bind /dev /mnt/root/dev
mount -o bind /sys /mnt/root/sys
mount -o bind /proc /mnt/root/proc
mount /dev/sda1 /mnt/root/boot
grub2-mkconfig -o /boot/grub2/grub.cfg
but that has no effect. Then I notice the following from the same VM recovery console:
sh-4.2# blkid /dev/sda2
whereas on the first good VM that boots fine ( both are clones of the same template ) I see the following:
# blkid /dev/sda2
/dev/sda2: UUID="owcjYz-ohz3-3obA-KaL0-wcyn-ayc5-EG1Fgc" TYPE="LVM2_member"
So based on the error that it can't find centos-root at boot time, I began to suspect it's because /dev/sda2 is set to PTTYPE="dos" rather then TYPE="LVM2_member" instead:
But how do I change this on /dev/sda2? I tried:
tune2fs /dev/sda2 -U random
returns "Bad magic number in super-block while trying to open /dev/sda2" and "Couldn't find valid filesystem superblock."
Googling for this hasn't proven fruitfull. Using the search string "change partition type LVM2_member" yields fdisk pages showing how to change the partition type in fdisk, which I already did above.
Searching for "change UUID" results in tune2fs commands that won't work on the fdisk partition and will yield the above error. Searching for "PTTYPE" yields only pages with blkid output.
Would anyone be able to share how to change the TYPE and UUID of the /dev/sda2 partition once fdisk creates it?
Perhaps I should be using another command instead? All this would have to be done from the recovery console.
Detailed blkid output of the good disk:
[root@sys01 ~]# blkid -po udev /dev/sda2
blkid of the bad disk ( host sys02 ):
sh-4.2# blkid -po udev /dev/sda2