OpenVZ is a virtualization software that allows multiple containers to share a single Linux kernel while providing features like live migration and quick backups. Containers are full Linux systems with separate user databases and network interfaces, and they can be managed using tools such as vzctl and vzlist. The document provides an introduction to the setup and configuration of OpenVZ, as well as advanced features and helpful references.

1. Introduction to OpenVZ
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Olle E.
oej@edvina.net Johansson * oej@edvina.net * Twitter oej
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2. OpenVZ
• Virtualization software by Parallells, inc.
Base for their commercial Virtuozzo
platform
• Integrated with the virtualization
support in the kernel - lvc
• Segmentation, not full virtualization
• Regardless, has cool features
Introduction to
OpenVZ

3. Cool features
• Migration of running system
• Backup with just a few secs stop time
• Very simple - shared filesystem in the
host system
Introduction to
OpenVZ

4. Basics
Containers share the
same kernel. Only Linux is
supported - but you can run
Kernel a different distribution in
Container 1 a container.
OpenVZ
The host system
Containers get allocated a few
runs a full Linux with a
Container 2 resources - network, CPU,
standard kernel with
memory, disk.
openvz extensions.
Introduction to
OpenVZ

5. The container is a full
Linux system
• The container is a full Linux system
• It has network interfaces (if configured)
• It has a separate user account database (/etc/passwd)
• It needs patching and updates like any other system
Introduction to
OpenVZ

6. The Kernel
• The kernel is managed as an package for
the distro you are using.
• For Centos, you add a new yum
repository and install the kernel
• Reboot and you have OpenVZ support
• Now install the tools - vzsplit, vzctl and
vzlist
Introduction to
OpenVZ

7. vzctl
• Used to manage containers
• Create new container
• Start container
• Stop container
• Change attributes (name, IP address, various limits,
properties)
Introduction to
OpenVZ

8. vzlist
• Simply list containers running in a system
• Lists all container IDs
Introduction to
OpenVZ

9. vzsplit
• Used to get settings for vzctl (or the .conf
files)
• Takes all resources in a server and divides
them between a specific number of
containers
Introduction to
OpenVZ

10. Beancounters
• Counters that document use
• Also document when a resource limit is
exceeded
• cat /proc/user_beancounters
• Used to design system and manage issues
• Watch the failcnt column!
Introduction to
OpenVZ

11. Networking
• Ethernet interface via nat or bridge
• The bridge interface enables DHCP and
other broadcast /multicast technologies
• IPv4 and IPv6 support
• Firewall with IPtables in container or
outside in host system (on the bridge)
• Network traffic can be managed Introduction to
OpenVZ

12. Script hooks
• There are hooks for scripts you can run
when starting and stopping containers
• These can be used to mount disk drives
into container
Introduction to
OpenVZ

13. Configuration
• Configuration file in /etc/vz/vz.conf
• Configuration for containers in /etc/vz/
conf
Introduction to
OpenVZ

14. Advanced features
• Live migration of containers between
systems
• Backup of running system
• Remote management with libvirt
Introduction to
OpenVZ

15. References
• www.openvz.org
• Documentation
• Wiki full with information, howto’s and documentation
• Downloadable templates for containers - Centos,
Debian, Ubuntu and other distributions
Introduction to
OpenVZ