I wrote up a HOWTO for the CentOS wiki entitled, Installing and using OpenVZ on CentOS 5, and thought I would share it here as well.
Please note that the OpenVZ kernel is a product of the OpenVZ Project
and is NOT supported by CentOS. The OpenVZ Project follows the RHEL
kernels closely and provides updates in a somewhat timely fashion
after updated Red Hat (and CentOS) kernels are released. As a result
the RHEL-based OpenVZ kernels are well suited for use on RHEL and
CentOS hosts with support for (almost) all of the same hardware.
Please note though that the OpenVZ kernel is less modular than the
stock Red Hat / CentOS kernels with some hardware support being
compiled in.
It is recommended you read this HOWTO in its entirety before
attempting any of the operations shown in it.What is OpenVZ?
OpenVZ is operating system-level virtualization based on a modified Linux kernel that allows a physical server to run multiple isolated instances known as containers, virtual private servers (VPS), or virtual environments (VE). The preferred term these days is container. Containers are sometimes compared to chroot or jail type environments but containers are really much better in terms of isolation, security, functionality, and resource management.
OpenVZ consists of a custom Linux kernel (available from the OpenVZ Project) and some user-level tools. OpenVZ is very portable, does not rely on VT support in the CPU, and as a result it is available for a number of CPU families including x86, x86-64, IA-64, PowerPC and SPARC.
OS-level virtualization is quite different from machine / hardware virtualization products such as VMware Server, Parallels Workstation, VirtualBox, QEMU, KVM, and Xen in that with OpenVZ you can only do Linux on Linux virtualization.
OpenVZ modifies the Linux kernel to add advanced containerization features which allow for isolated groups of processes under a parent init along with about twenty dynamic resource management parameters for controlling container resource usage. The OpenVZ Project maintains three stable kernel branches:
- RHEL4 / CentOS4 2.6.9 based
- RHEL5 / CentOS 5 2.6.18 based
- Vanilla 2.6.18 based
There are a number of unstable branches based on newer versions of the Linux kernel that may eventually reach stable status.
