Virtuozzo
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| Parallels Virtuozzo Containers | |
|---|---|
| Developed by | Parallels, Inc. |
| Latest release | 4.0 / January 2008 |
| OS | Windows and Linux |
| Platform | x86, x86-64, IA-64 |
| Genre | OS-level virtualization |
| Website | Virtuozzo |
Parallels Virtuozzo Containers is a proprietary operating system-level virtualization product produced by Parallels, Inc. A version that supports Linux has been available since 2001; a version that supports Microsoft Windows became available in 2005.
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[edit] Description
Parallels Virtuozzo Containers creates multiple, isolated containers (otherwise known as virtual environments, or VEs), or Virtual Private Servers, or VPSs), on a single physical server. This allows the sharing of hardware, systems management effort, and sometimes software licenses among different workloads.
A container behaves in most respects as if it were a stand-alone server. Each container has its own superuser (root or Administrator), set of users/groups, IP address(es), processes, files, applications, system libraries and configuration files. Container is completely accessible via the network. Due to virtualized network stack, a container owner can have his own routing tables and firewall (iptables) rules.
Parallels Virtuozzo Containers can support tens to hundreds of containers on a single server due to its use of operating system-level virtualization.[citation needed] The host OS can be Linux or Windows. With a Windows host OS, the virtual environments on the server have to be the same OS as the host OS. For example, a host machine running Windows 2003 would have containers also running Windows Server 2003. The Linux edition is more flexible, allowing containers to appear to have different distributions of Linux.
[edit] Operating system-level virtualization
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For more details on this topic, see Operating system-level virtualization.
Parallels Virtuozzo Containers virtualizes at the operating system level, rather than the hardware level as other Virtual Machine (VM) products frequently do. Whereas VMs attempt to virtualize "a complete set of hardware," containers represent a "lighter" abstraction, virtualizing instead "an operating system instance". All containers run atop a single operating system kernel. The containerization mechanisms multiplexes this one OS kernel to look like multiple OS (and server) instances, especially from the perspective of running applications, users, and network services. Parallels Virtuozzo Containers for Linux is based on OpenVZ, which is available under the GNU General Public License, and its concepts are similar to several other operating system-level virtualization implementations, including HP-UX Secure Resource Partitions, Solaris Containers, Linux-VServer and FreeBSD Jail.
Because they virtualize less, containers impose lower overhead than VMs. As a result, more containers can be supported on a given server. Parallels Virtuozzo Containers supports servers with up to 64 CPUs and 64 GB of RAM.
[edit] Comparison to other technologies
Parallels Virtuozzo Containers employs a virtualization approach which differs from most other virtualization technologies. Parallels Virtuozzo Containers was designed to be a low-overhead, fast-performing solution with many tools for simple management, since its early adopters include service providers with thousands of containers to manage. The technology is based on a single OS flavor for a server, which means that a Windows server can only host Windows containers and that a Linux servers can only host Linux containers.
Since 2001, Parallels Virtuozzo Containers has been running in service provider environments, which house hundreds of different customers on a single server, without an external firewall. Because they rely on the services of a single kernel, all containers on a given server run the same kernel, but everything else — system libraries, configuration and program files — can be different in different containers. That means that different Linux distributions can coexist on a single Parallels Virtuozzo Containers for Linux server.
