This document briefly describes the steps needed is a guide to install OpenVZ 6 (legacy) on your Debian 9 "Stretch" (amd64 or i386) machine.

{{Note|The best and latest Debian version for OpenVZ 6 is [[Installation on Debian 8|Devuan 1.0]], but Debian 9 makes really easy the coexistence of OVZ and unprivileged LXC containers.}}{{Out|Current commercial version of OpenVZ ([[Virtuozzo]] 7) is not installable on Devuan or Debian GNU/Linux because is developed as an independent GNU/Linux distribution}}

== Requirements ='''Volumes and file systems''' =

Debian GNUIt is recommended to use a separate partition for containers (by default '''/Linux without "64bit" feature at Ext4 filesystemvar/lib/vz''') and format it to '''compatible ext4'''.

== Filesystem and defaults Ext4 ==Debian 9 installer (and tools by default) formats Ext4 with new features, and concrete "metadata_csum" is incompatible with OpenVZ6 kernel. Then it's necessary to boot without requiring the mount of volumes with "metadata_csum". Ordered alternatives:# After a fresh Debian 9 install, remove metadata_csum feature from filesystems.# Upgrade from Debian 8 to Debian 9 (metadata_csum not inherited)# Root volume (/ and others) as Ext3 and deploy /var/lib/vz in a later created Ext4 volume, without metadata_csum.# Use Ext3

Debian 9 installer formats Ext4 with new features (64bit === How to remove metadata_csum) from a mounted partition ===If your host altready mounts r/w volumes on boot and you can't tune2fs+e2fsck because volumes are in use, this is incompatible with OpenVZ6 kernel the solution (initrd cannot mount rootexample for /dev/sda1):* First check if the partition is affected. Then it Volume=/dev/sda1 sudo dumpe2fs -h $Volume 2>/dev/null | grep -e metadata_csum* If last command didn's necessary t return a line with metadata_csum, nothing to boot without requiring the mount of this advanced formatdo. OptionsOtherwise, continue: echo copy_exec /sbin/e2fsck | sudo tee -a /usr/share/initramfs-tools/hooks/fsck echo copy_exec /sbin/tune2fs | sudo tee -a /usr/share/initramfs-tools/hooks/fsck Script=/etc/initramfs-tools/scripts/local-premount/tune echo '#!/bin/sh' | sudo tee $Script echo 'if [ "$1" = "prereqs" ] ; then exit 0 ; fi' | sudo tee -a $Script echo e2fsck -f $Volume | sudo tee -a $Script echo tune2fs -O -metadata_csum $Volume | sudo tee -a $Script echo e2fsck -f $Volume | sudo tee -a $Script sudo chmod a+x $Script sudo update-initramfs -u -k all* Root volume Reboot and check that metadata_csum disappeared: sudo reboot (...) Volume=/) as Ext3 and dev/varsda1 sudo dumpe2fs -h $Volume 2>/libdev/vz separated in an Ext4null | grep -e metadata_csum* Install Debian 8 (will format without "64bit") and upgrade Restore initrd behaviour sudo rm /etc/initramfs-tools/scripts/local-premount/tune sudo apt --reinstall install initramfs-tools-core sudo update-initramfs -u -k allThis recipe is useful for any volume that can't be neither unmounted nor remounted readonly. === How to Debian 9remove metadata_csum from a not mounted partition ===This procedure can be applied when partition can be mounted readonly* Install Debian 9 Example for /dev/sda9 sudo e2fsck -f /dev/sda9 sudo tune2fs -O -metadata_csum /dev/sda9 sudo e2fsck -f /dev/sda9 === How to format a volume to be a previously formatted compatible Ext4 without "64bit".===* Example for /dev/sda9 sudo mkfs -t ext4 -O -metadata_csum /dev/sda9

== Partitions and btrfs ==You might want btrfs to use per-directory (subvolume) quotas for other simfs/dir containers, such as LXC. Only vzquota doesn't work on a btrfs volume; for OVZ containers it's better to mount /var/lib/vz file system ==to an Ext4 volume.

It is recommended to use a separate partition for containers Debian 9 installer (and tools by default '''/var/lib/vz''') and format formats btrfs with modern features as: mixed-bg, extref, skinny-metadata, no-holes. All of these are incompatible with OpenVZ6 kernel. Then it 's necessary to '''ext4'''boot without requiring the mount of volumes with these attributes.Ordered alternatives:

=== How to format a volume to be a compatible btrfs ===* Example for /dev/sda1 sudo mkfs -t btrfs -O ^mixed-bg,^extref,^skinny-metadata,^no-holes /dev/sda1You must not format btrfs with Debian installer because features cannot be disabled after. = '''Change Systemd to SystemV''' = {{Note|Warning! This operation can make some desktop software to stop working, such as desktop environments.}}

echo -e 'Package: *systemd*\nPin: release *\nPin-Priority: -1\n' | sudo tee /etc/apt/preferences.d/avoid-systemd

* Other More recipes at [http://without-systemd.org/wiki/index.php/Debian_Stretch without-systemd.org]

== '''Register OVZ updated repository =''' =

== '''Install packages =''' =

sudo apt --allow-unauthenticated --install-recommends install $KPackage vzdump ploop initramfs-toolsdirmngr

== '''Reboot into OpenVZ kernel ''' == {{Note|At boot manager, in "Advanced options for Debian GNU/Linux", you will find kernels named "2.6.32-openvz". Select the first listed.}}

{{Note|If you don't see a boot manager entry with word "'''openvz'''", you must choose "'''Advanced options'''" to select there first ''openvz'' listed kernel.}} Check that the OpenVZ processes are running:

Because of GRUB2 default criteria, default kernel to boot can still be the one from Debian's repository (non OVZ). If Probably you don't want to change this behaviour, ; once you've booted fine into OpenVZ kernel, you can remove other unuseful kernels:

== Download OS templates ==

An OS template is a GNU distribution for Linux distribution , installed into a container

Alternatively, you can also download Alternatives:* Download precreated template caches from [http://openvz.org/download[Download/template/cache Downloads precreated|Download » Templates Template » Precreated], ] or from one of the [https://mirrors.openvz.org/ mirrors]. Put those tarballs '''as-is (no unpacking needed)''' to the <tt>/vz/template/cache/</tt> directory.* '''[https://downloads.actiu.net/ctctl/ ctctl]''' helper to create Debian (or derivative) container without template (caches it as a local template). This tool manages unprivileged LXC containers too.

== Next steps ==

== See also ==* [[Installation on Debian 8]] (oldstable) or Devuan 1.0 (Jessie, stable, SystemV)