- Virtual private server
Types of Internet hosting service Full-featured hosting Virtual private server · Dedicated hosting · Colocation centre · Cloud hosting Web hosting Free hosting · Shared · Clustered · Reseller Application-specific web hosting Blog (comments) · Guild hosting · Image · Video · Wiki farms · Application · Social network By content format File · Image · Video · Music Other types Remote backup · Game server · DNS · E-mail
Virtual private server (VPS) is a term used by Internet hosting services to refer to a virtual machine. The term is used for emphasizing that the virtual machine, although running in software on the same physical computer as other customers' virtual machines, is functionally equivalent to a separate physical computer, is dedicated to the individual customer's needs, has the privacy of a separate physical computer, and can be configured to run as a server computer (i.e. to run server software). The term Virtual Dedicated Server or VDS is used less often for the same concept, however it may indicate that the server does not use burst/shared ram through multiple machines, as well as individual CPU cores.
In addition to reducing hardware and power expenditures, virtualisation allows businesses to run their legacy applications on older versions of an operating system on the same server as newer applications.
Each virtual server can run its own full-fledged operating system and can be independently rebooted.
The practice of partitioning a single server so that it appears as multiple servers has long been common practice on mainframe computers and mid-range computers such as the IBM AS/400. It has become more prevalent with the development of virtualization software and technologies for microcomputers.
The physical server typically runs a hypervisor which is tasked with creating, releasing, and managing the resources of "guest" operating systems, or virtual machines. These guest operating systems are allocated a share of resources of the physical server, typically in a manner in which the guest is not aware of any other physical resources save for those allocated to it by the hypervisor.
The Guest system may be fully virtualized, paravirtualized, or a hybrid of the two.
In a fully virtualized environment, the guest is presented with an emulated or virtualized set of hardware and is unaware that this hardware is not strictly physical. The hypervisor in this case must translate, map, and convert requests from the guest system into the appropriate resource requests on the host, resulting in significant overhead. Almost all systems can be virtualized using this method, as it requires no modification of the operating system, however a CPU supporting virtualization is required for most hypervisors that perform full virtualization.
In a paravirtualized environment, the guest is aware of the hypervisor and interfaces directly with the host system's resources, with the hypervisor implementing real-time access control and resource allocation. This results in near-native performance since the guest sees the same hardware as the host and can thus communicate with it natively. UNIX-like systems, such as Linux, some variants of BSD, Plan9, and OpenSolaris are currently known to support this method of virtualization. However, installing operating systems as paravirtualized guests tends to require more knowledge about the operating system in order to have it use special hypervisor-aware kernels and devices.
Hybrid or partial paravirtualization, is full virtualization, but in which the guest uses paravirtualized drivers for key components such as Networking and Disk I/O, resulting in greatly increased I/O performance. As such, it is a common solution for operating systems which cannot be modified (for various reasons) to support paravirtualiztion.
One example of a hybrid hypervisor is Kernel-based Virtual Machine.
Virtual private servers bridge the gap between shared web hosting services and dedicated hosting services, giving independence from other customers of the VPS service in software terms but at less cost than a physical dedicated server. As a VPS runs its own copy of its operating system, customers have superuser-level access to that operating system instance, and can install almost any software that runs on the OS. Certain software does not run well in a virtualized environment, such as virtualizers themselves; some VPS providers place further restrictions, but they are generally lax compared to those in shared hosting environments. Due to the number of virtualization clients typically running on a single machine, a VPS generally has limited processor time, RAM, and disk space.
Virtual private server hosting
A growing number of companies offer virtual private server hosting, or virtual dedicated server hosting as an extension for web hosting services. There are several challenges to consider when licensing proprietary software in multi-tenant virtual environments.
The customer is left to monitor and administer their own server.
This type of service is generally offered with no limit on the amount of data-transferred on a fixed bandwidth line. Usually, unmetered hosting is offered with 10 Mbit/s, 100 Mbit/s or 1000 Mbit/s (with some as high as 10Gbit/s). This means that the customer is theoretically able to use 3.33~ TB on 10 Mbit/s, 33~ TB on 100 Mbit/s and 333~ TB on a 1000 Mbit/s line per month (although in practice the values will be significantly less).
A VPS which is dynamic (that is, it can be changed at runtime) is often referred to as a cloud server. Key attributes for this are:
- Additional hardware resources can be added at runtime (CPU, RAM)
- Server can be moved to other hardware while the server is running (automatically according to load in some cases)
See Cloud computing for more information.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Virtual Private Server — Serveur dédié virtuel Un serveur dédié virtuel (également appelé serveur virtuel), en anglais virtual private server ou virtual dedicated server est une méthode de partitionnement d un Serveur en plusieurs serveurs virtuels indépendants qui ont… … Wikipédia en Français
Virtual dedicated server — Serveur dédié virtuel Un serveur dédié virtuel (également appelé serveur virtuel), en anglais virtual private server ou virtual dedicated server est une méthode de partitionnement d un Serveur en plusieurs serveurs virtuels indépendants qui ont… … Wikipédia en Français
Virtual file server — In computing, a virtual file server is a device (physical or virtualized) that has the primary purpose of providing a location for the distributed storage of computer files (such as documents, sound files, photographs, movies, images, databases,… … Wikipedia
Virtual Private LAN Service — (VPLS) is a way to provide Ethernet based multipoint to multipoint communication over IP/MPLS networks. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting sites through pseudo wires. The technologies that … Wikipedia
Virtual Private Network — (deutsch „virtuelles privates Netz“; kurz „VPN“) ist eine Schnittstelle in einem Netzwerk und hat zwei unterschiedliche Bedeutungen. Das konventionelle VPN dient dazu, Teilnehmer eines Netzes an ein anderes Netz zu binden, ohne dass die Netzwerke … Deutsch Wikipedia
Virtual private network — A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The link layer protocols… … Wikipedia
Virtual Private Network — VPN (англ. Virtual Private Network виртуальная частная сеть) логическая сеть, создаваемая поверх другой сети, например Интернет. Несмотря на то, что коммуникации осуществляются по публичным сетям с использованием небезопасных протоколов, за счёт… … Википедия
Virtual Private Network — Réseau privé virtuel Pour les articles homonymes, voir VPN. Dans les réseaux informatiques et les télécommunications, le réseau privé virtuel (Virtual Private Network en anglais, abrégé en VPN) est vu comme une extension des réseaux locaux et… … Wikipédia en Français
Virtual server — may refer to:* Microsoft Virtual Server, a virtualization product produced by Microsoft based on Connectix technology. * Virtual private server, a method of server hosting using virtual machines. * Virtual hosting, a method that servers such as… … Wikipedia
Virtual hosting — Not to be confused with Virtual private server. Virtual hosting is a method for hosting multiple domain names on a server using a single IP address. This allows one server to share its resources, such as memory and processor cycles, in order to… … Wikipedia