OpenVZ

Virtuozzo & OpenVZ RHEL6
OpenVZ (Open Virtuozzo) is an operating-system-level virtualization technology for Linux.wikipedia
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OS-level virtualization

operating-system-level virtualizationcontainersoperating system-level virtualization
OpenVZ (Open Virtuozzo) is an operating-system-level virtualization technology for Linux.
Such instances, called containers (Solaris, Docker), Zones (Solaris), virtual private servers (OpenVZ), partitions, virtual environments (VEs), virtual kernel (DragonFly BSD) or jails (FreeBSD jail or chroot jail), may look like real computers from the point of view of programs running in them.

LXC

LXC containersContainerLinux containers
OpenVZ is similar to Solaris Containers and LXC. Up to version 3.4, Proxmox VE could be used as an OpenVZ-based server virtualization environment with a GUI, although later versions switched to LXC.
Originally, LXC containers were not as secure as other OS-level virtualization methods such as OpenVZ: in Linux kernels before 3.8, the root user of the guest system could run arbitrary code on the host system with root privileges, much like chroot jails.

Live migration

live migratedlive-migratemigrating
A live migration and checkpointing feature was released for OpenVZ in the middle of April 2006.

Proxmox Virtual Environment

Proxmox VEProxmox
Up to version 3.4, Proxmox VE could be used as an OpenVZ-based server virtualization environment with a GUI, although later versions switched to LXC.
Two types of virtualization are supported: container-based with LXC (starting from version 4.0 replacing OpenVZ used in version up to 3.4, included ), and full virtualization with KVM.

Virtuozzo (company)

VirtuozzoParallels Virtuozzo Containers
OpenVZ (Open Virtuozzo) is an operating-system-level virtualization technology for Linux.
Virtuozzo developed the first commercially available operating system-level virtualization container technology in 2000 which was open-sourced in 2005 in the form of OpenVZ.

Comparison of platform virtualization software

Comparison of platform virtual machineshardware levelplatform hypervisors

Linux

GNU/LinuxLinux on the desktopLin
OpenVZ (Open Virtuozzo) is an operating-system-level virtualization technology for Linux.

Virtual private server

cloud serverVPSserver virtualization
It allows a physical server to run multiple isolated operating system instances, called containers, virtual private servers (VPSs), or virtual environments (VEs).

VMware

VMware, Inc.HypericVMotion
While virtualization technologies such as VMware and Xen provide full virtualization and can run multiple operating systems and different kernel versions, OpenVZ uses a single Linux kernel and therefore can run only Linux.

Xen

XenServerXenSourceXen Cloud Platform
While virtualization technologies such as VMware and Xen provide full virtualization and can run multiple operating systems and different kernel versions, OpenVZ uses a single Linux kernel and therefore can run only Linux.

Hypervisor

hypervisorsvirtual machine monitorhost machine
However, as it does not have the overhead of a true hypervisor, it is very fast and efficient.

Disk buffer

buffercachedisk caching
Memory allocation with OpenVZ is soft in that memory not used in one virtual environment can be used by others or for disk caching.

Chroot

chroot jailchroot "jailsChroot jails
While old versions of OpenVZ used a common file system (where each virtual environment is just a directory of files that is isolated using chroot), current versions of OpenVZ allow each container to have its own file system.

Linux kernel

LinuxLinux kernel mainlinekernel
The OpenVZ kernel is a Linux kernel, modified to add support for OpenVZ containers.

Application checkpointing

checkpointingcheckpointCheckpoint restart
A live migration and checkpointing feature was released for OpenVZ in the middle of April 2006. The modified kernel provides virtualization, isolation, resource management, and checkpointing.

Library (computing)

librarylibrariessoftware library
;Files: System libraries, applications, virtualized and, virtualized locks, etc.

Application software

applicationapplicationssoftware application
;Files: System libraries, applications, virtualized and, virtualized locks, etc.

Lock (computer science)

lockmutexlocks
;Files: System libraries, applications, virtualized and, virtualized locks, etc.

Superuser

rootroot accessroot user
;Users and groups: Each container has its own root user, as well as other users and groups.

User (computing)

userusernameusers
;Users and groups: Each container has its own root user, as well as other users and groups.

Group (computing)

groupsgroup
;Users and groups: Each container has its own root user, as well as other users and groups.

Process (computing)

processprocessesprocessing
;Process tree: A container only sees its own processes (starting from init).

Init

sysvinitinit systeminit process
;Process tree: A container only sees its own processes (starting from init). PIDs are virtualized, so that the init PID is 1 as it should be.

Process identifier

PIDprocess IDPIDs
PIDs are virtualized, so that the init PID is 1 as it should be.