Mdthbs

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



mkdir /mnt/root

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



chroot /mnt/root



cd /boot

dracut -f

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

/dev/sda2: PTTYPE="dos"

sh-4.2#

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

ID_FS_UUID=owcjYz-ohz3-3obA-KaL0-wcyn-ayc5-EG1Fgc

ID_FS_UUID_ENC=owcjYz-ohz3-3obA-KaL0-wcyn-ayc5-EG1Fgc

ID_FS_VERSION=LVM2x20001

ID_FS_TYPE=LVM2_member

ID_FS_USAGE=raid

ID_PART_ENTRY_SCHEME=dos

ID_PART_ENTRY_TYPE=0x8e

ID_PART_ENTRY_NUMBER=2

ID_PART_ENTRY_OFFSET=1026048

ID_PART_ENTRY_SIZE=133191680

ID_PART_ENTRY_DISK=8:0

[root@sys01 ~]#

blkid of the bad disk ( host sys02 ):

sh-4.2# blkid -po udev /dev/sda2

ID_PART_TABLE_TYPE=dos

ID_PART_TABLE_SCHEME=dos

ID_PART_ENTRY_TYPE=0x8e

ID_PART_ENTRY_NUMBER=2

ID_PART_ENTRY_OFFSET=1026048

ID_PART_ENTRY_SIZE=133191680

ID_PART_ENTRY_DISK=8:0

sh-4.2#

Thx,
TK

Posted this earlier but I suppose I had the wrong forum over at StackExchange -> Superuser?