Linux-VServer: Difference between revisions

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Latest revision as of 22:33, 26 April 2023

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{{Short description|OS-level virtualisation}}

{{multiple|

{{primary sources|date=May 2014}}

{{Citations|date=January 2014}}

}}

{{Infobox software

| name =

| logo = [[Image:Linux-VServer-logo.png|Linux-VServer]]

| screenshot =

| caption =

| developer = Herbert Pötzl (Community Project)

| latest release version = 2.6.22.19-vs2.2.0.7

| latest release date = {{start date and age|2008|03|14}}

| latest preview version = 4.9.159-vs2.3.9.8

| latest preview date = {{start date and age|2019|10|05}}

| operating_system = [[Linux]]

| platform = [[x86]], [[x86-64]], [[SPARC|SPARC/64]], [[PA-RISC]], [[S390|S390z/xArchitecture|s390x]], [[MIPS architecture|MIPS/64]], [[ARM architecture|ARM]], [[PowerPC|PowerPC/64]], [[Itanium]]

| genre = [[Operating system-level virtualization|OS-level virtualization]]

| license = [[GNU General Public License|GNU GPL]] v.2

| website = [http://{{URL|linux-vserver.org/ Linux-VServer.org]}}

}}

'''Linux-VServer''' is a [[virtual private server]] implementation that was created by adding [[operating system-level virtualization]] capabilities to the [[Linux kernel]]. It is developed and distributed as [[open-source software]].

==Details==

The project was started by [[Jacques Gélinas]]. It is now maintained by Herbert Pötzl. of [[Austria]] andIt is not related to the [[Linux Virtual Server]] project, which implements network [[Load balancing (computing)|load balancing]].

Linux-VServer is a [[jailOperating-system-level (computer security)virtualization|jail mechanism]] in that it can be used to securely partition resources on a computer system (such as the [[file system]], CPU time, network addresses and memory) in such a way that [[process (computing)|processes]] cannot mount a [[denial-of-service attack]] on anything outside their partition.

Each partition is called a ''security context'', and the virtualized system within it is the ''virtual private server''. A [[chroot]]-like utility for descending into security contexts is provided. Booting a virtual private server is then simply a matter of kickstarting [[init]] in a new security context; likewise, shutting it down simply entails killing all processes with that security context. The contexts themselves are robust enough to boot many [[Linux distribution]]s unmodified, including [[Debian]] and [[Fedora (operating system)|Fedora]].

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* Virtual servers share the same [[system call]] interface and do not have any [[emulator|emulation]] overhead.

* Virtual servers do not have to be backed by opaque [[disk image]]s, but can share a common file system and common sets of files (through copy-on-write hard links). This makes it easier to back up a system and to pool disk space amongst virtual servers.

* Processes within the virtual server run as regular processes on the host system. This is somewhat more memory-efficient and I/O-efficient than whole-system emulation, whichalthough cannotmemory returnballooning and modern VMs allow returning "unused" memory or shareand asharing disk cache with the host and other virtual servers.

* Processes within the virtual server are queued on the same scheduler as on the host, allowing guestsguest's processes to run concurrently on [[Symmetric multiprocessing|SMP]] systems. This is not trivial to implement with whole-system emulation.

* Networking is based on isolation rather than virtualization, so there is no additional overhead for packets.

* Smaller plane for security bugs. Only one kernel with small additional code-base compared to 2+ kernels and large interfaces between them.

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==Disadvantages==

* Requires that the host kernel be patched.

* All virtual servers share the same kernel so all must be Linux. (Because of backwards compatibility in user-space API, this does not impair use of old Linux programs or distributions. {{Citation needed|date=April 2013}})

* No [[computer cluster|clustering]] or [[process migration]] capability is included, so the host kernel and host computer is still a single point of failure for all virtual servers.

* Networking is based on isolation, not virtualization. This prevents each virtual server from creating its own internal routing or firewalling setup.

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==See also==

{{Portal|Free and open-source software}}

* [[Comparison of platform virtualvirtualization machinessoftware]]

* [[Operating system-level virtualization]]

==References==

;Similar virtualization mechanisms

{{Reflist}}

* [[Operating system-level virtualization#Implementations|Other implementations of operating system-level virtualization technology]]

==External links==

* [http://linux-vserver.org/ {{Official website]}}

* [http://www.13thfloor.at/vserver/project/ Official releases]

* [http://linux-vserver.org/Linux-VServer-Paper Implementation paper]

{{Virtualization software}}

{{Linux kernel}}

{{DEFAULTSORT:Linux-Vserver}}

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[[Category:Linux kernel features]]

[[Category:Free virtualization software]]

[[Category:Linux-only free software]]

[[Category:Virtualization software for Linux]]