1 post

Migration of OpenVZ Container to KVM Guest

This is a short tutorial how to migrate an OpenVZ container to a KVM Guest. Some ideas have been taken from other tutorials(( https://www.pither.com/simon/blog/2011/09/20/convert-an-openvz-vm-to-kvm )) (( http://blog.smile.fr/Migrate-your-openvz-containers-to-kvm-openstack )), the other half has been extracted from grml-debootstrap which can generate a KVM guest by using debootstrap.

 # form where to where migrate
 # don't forget the trailing / on the source!
 export SOURCE=/srv/vz/private/xxxxxxx/
 # an empty LVM volume!
 export DEST=/dev/mapper/vg0-myfirstvm

 # create some magic for grub/partion table
 echo 4 66 | /usr/share/grml-debootstrap/bootgrub.mksh -A | sudo dd of=${DEST} conv=notrunc
 sudo dd if=/dev/zero bs=1 conv=notrunc count=64 seek=446 of=${DEST}

 # this is a partition with a partion table on on its own
 sudo kpartx -av ${DEST}
 # create partition
 sudo parted -s "${DEST}" 'mkpart primary ext4 2M -1'
 # create filesystem
 sudo mkfs.ext4 "${DEST}p1"

 # mount it
 sudo mount "${DEST}p1" /mnt

 # not it's time to rsync your files to the destination folder (/mnt)
 sudo rsync -av --numeric-ids --stats --progress ${SOURCE}/ /mnt

 # mount some needed thins inside the KVM guest
 sudo mount -t proc none /mnt/proc
 sudo mount -t sysfs none /mnt/sys
 sudo mount --bind /dev /mnt/dev 

 # fix fstab
 echo `sudo blkid -o export  "${DEST}p1" |grep UUID `  /  ext4   defaults,noatime   0 0   | sudo tee -a /mnt/etc/fstab

 # install kernel + grub + acpi
 # IMPORTANT: during install you are asked to install grub - DO NOT install on any disks/partitions!
 sudo chroot /mnt aptitude install linux-image-amd64 linux-headers-amd64 busybox firmware-linux-free firmware-linux grub-pc acpid acpi-support-base
 # the last command installed and started acpid, so we need to stop it again
 sudo chroot /mnt service acpid stop
 # configure grub
 sudo chroot /mnt/ grub-mkimage -O i386-pc -p '(hd0,msdos1)/boot/grub' -o /tmp/core.img biosdisk part_msdos ext2
 # ATTEENTION: wheezy uses an old gurb and you need to copy it to boot/grub directly!
 sudo cp -rp /mnt/usr/lib/grub/i386-pc /mnt/boot/grub
 sudo dd if=/mnt/tmp/core.img of=$DEST conv=notrunc seek=4
 sudo chroot /mnt  update-grub

 # cleanup
 sudo umount /mnt/proc
 sudo umount /mnt/sys
 sudo umount /mnt/dev
 sudo umount /mnt
 sudo kpartx -d "${DEST}"

 # you may need to remount and rerun 'update-grub'
 # you should check /boot/grub/gurb.cfg within the virtual server that the linux kernel command arguments contain the correct root parameter (with a UUID)!
 # create the KVM VM with virt-install (see my previous post about KVM)

Update 2016/09/20: with some minor fixes and one missing command (copy grub/i386-pc directory)
Update 2016/10/04: I’ve found one more interesting post by ch: https://christian.hofstaedtler.name/blog/2012/07/openvz-to-kvm.html