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Machine/template-focal (view source)
Revision as of 11:48, 16 November 2020
, 11:48, 16 November 2020→VM Creation (host part)
#* OpenSSH server
#* OpenSSH server
# GRUB: let the installer setup grub on /dev/vda (which contains /boot)
# GRUB: let the installer setup grub on /dev/vda (which contains /boot)
== Switch the root filesystem to an LV ==
When the machine is offline, go to the host to recreate the root filesystem directly as an LV (as opposed to a partitioned volume)
First of all, we need to set up the device mapping for the first and only partition where the root filesystem resides.
kpartx -av /dev/justice/template-focal-root
Mount the root partition:
mkdir /mnt/template-focal-root
mount /dev/mapper/justice-template--focal-root1 /mnt/template-focal-root
Now create and format a new LV:
lvcreate -L 10G -n template-focal-root2 justice
mkfs.ext4 -L template-focal -O flex_bg,extent,uninit_bg,sparse_super /dev/justice/template-focal-root2
tune2fs -c -1 -i 0 /dev/justice/template-focal-root2
mkdir /mnt/template-focal-root2
mount /dev/justice/template-focal-root2 /mnt/template-focal-root2
Move the files over:
rsync -HAXphax --numeric-ids /mnt/template-focal-root/ /mnt/template-focal-root2/
'''NOTE''': By default, Ubuntu 20.04 uses UUID in /etc/fstab in order to mount partitions. Since we have changed the root
partition to a new disk, the UUID will change. Aside from that, the grub.cfg also specifies the location of the root filesystem
using UUID notation (ex: /vmlinuz-4.4.0-89-generic root=UUID=0ad5d004-e5dd-4b93-abe4-2bb0ba4fd94a).
Before we umount the filesystems, let's create a chroot environment and fix previous issues:
kpartx -av /var/lib/libvirt/images/boot/template-focal-boot.img
mount /dev/mapper/loop0 /mnt/template-focal-root2/boot
mount --bind /dev/ /mnt/template-focal-root2/dev/
mount -t proc proc /mnt/template-focal-root2/proc/
mount -t sysfs sys /mnt/template-focal-root2/sys/
chroot /mnt/template-focal-root2/
Once inside the chroot environment:
* Fix serial console access by making getty listen on /dev/ttyS0:
systemctl enable serial-getty@ttyS0.service
* Replace UUID with device name for root fs location inside /boot/grub/grub.cfg
sed -i -r "s/root=UUID=[0-9a-f-]+/root=\/dev\/vdb/" /boot/grub/grub.cfg
* Adjust /etc/fstab to mount the filesystems from "LABEL=boot" and "LABEL=template-focal".
Finally (VERY IMPORTANT), umount all filesystems before starting the VM:
umount /mnt/template-focal-root2/boot/
umount /mnt/template-focal-root2/dev/
umount /mnt/template-focal-root2/proc/
umount /mnt/template-focal-root2/sys/
umount /mnt/template-focal-root2/ /mnt/template-focal-root/
Get rid of the old root and rename the new one on top of it
kpartx -d /var/lib/libvirt/images/boot/template-focal-boot.img
lvremove /dev/justice/template-focal-root
lvrename justice template-focal-root2 template-focal-root
== Partitioning ==
== Partitioning ==