Virtual Machine

In computer science, a virtual machine (VM) is a software implementation of a machine (computer) that executes programs like a real machine.

A virtual machine is a type of computer application used to create a virtual environment, which is referred to as virtualization. Virtualization allows the user to see the infrastructure of a network through a process of aggregation. Virtualization may also be used to run multiple operating systems at the same time. Through the help of a virtual machine, the user can operate software located on the computer platform.
There are several different types of virtual machines. Most commonly, the term is used to refer to hardware virtual machine software, also known as a hypervisor or virtual machine monitor. This type of virtual machine software makes it possible to perform multiple identical executions on one computer. In turn, each of these executions runs an operating system. This allows multiple applications to be run on different operating systems, even those they were not originally intended for.
Through the use of the hardware virtual machine software, the user has a seemingly private machine with fully functional hardware that is separate from other users. Hardware virtual machine software also makes it possible for users to boot and restart their machines quickly, since tasks such as hardware initialization are not necessary.
Virtual machine can also refer to application virtual machine software. With this software, the application is isolated from the computer being used. This software is intended to be used on a number of computer platforms. This makes it unnecessary to create separate versions of the same software for different operating systems and computers. Java Virtual Machine is a very well known example of an application virtual machine.
A virtual machine can also be a virtual environment, which is also known as a virtual private server. A virtual environment is used for running programs at the user level. Therefore, it is used solely for applications and not for drivers or operating system kernels.
A virtual machine may also be a group of computers that work together to create a more powerful machine. In this type of virtual machine, the software makes it possible for one environment to be formed throughout several computers. This makes it appear to the end user as if he or she is using a single computer, when there are actually numerous computers at work.

• Implementation

Virtual machine implementation and dynamic languages
I'm looking for references to virtual machine implementations and dynamic languages.
I seem to recall something recently about what the Java VM lacks wrt dynamic languages and what other implementations (Parrot?) do that enable dynamic languages.
What would a Universal VM look like? Is such a thing possible?
I'm not googling the right keywords, I'm not finding what I'm looking for.

• Benefits

1. Designed for virtual machines running on Windows Server 2008 and Microsoft Hyper-V ServerHyper-V is the next-generation hypervisor-based virtualization platform from Microsoft, which is designed to offer high performance, enhanced security, high availability, scalability, and many other improvements. VMM is designed to take full advantage of these foundational benefits through a powerful yet easy-to-use console that streamlines many of the tasks necessary to manage virtualized infrastructure. Even better, administrators can manage their traditional physical servers right alongside their virtual resources through one unified console.
2. Support for Microsoft Virtual Server and VMware ESXWith this release, VMM now manages VMware ESX virtualized infrastructure in conjunction with the Virtual Center product. Now administrators running multiple virtualization platforms can rely on one tool to manage virtually everything. With its compatibility with VMware VI3 (through Virtual Center), VMM now supports features such as VMotion and can also provide VMM-specific features like Intelligent Placement to VMware servers.
3. Performance and Resource Optimization (PRO) Performance and Resource Optimization (PRO) enables the dynamic management of virtual resources though Management Packs that are PRO enabled. Utilizing the deep monitoring capabilities of System Center Operations Manager 2007, PRO enables administrators to establish remedial actions for VMM to execute if poor performance or pending hardware failures are identified in hardware, operating systems, or applications. As an open and extensible platform, PRO encourages partners to design custom management packs that promote compatibility of their products and solutions with PRO’s powerful management capabilities.
4. Maximize datacenter resources through consolidation A typical physical server in the datacenter operates at only 5 to 15 percent CPU capacity. VMM can assess and then consolidate suitable server workloads onto virtual machine host infrastructure, thus freeing up physical resources for repurposing or hardware retirement. Through physical server consolidation, continued datacenter growth is less constrained by space, electrical, and cooling requirements.
5. Machine conversions are a snap! Converting a physical machine to a virtual one can be a daunting undertaking—slow, problematic, and typically requiring you to halt the physical server. But thanks to the enhanced P2V conversion in VMM, P2V conversions will become routine. Similarly, VMM also provides a straightforward wizard that can convert VMware virtual machines to VHDs through an easy and speedy Virtual-to-Virtual (V2V) transfer process.
6. Quick provisioning of new machines In response to new server requests, a truly agile IT department delivers new servers to its business clients anywhere in the network infrastructure with a very quick turnaround. VMM enables this agility by providing IT administrators with the ability to deploy virtual machines in a fraction of the time it would take to deploy a physical server. Through one console, VMM allows administrators to manage and monitor virtual machines and hosts to ensure they are meeting the needs of the corresponding business groups.Quick provisioning of new machines In response to new server requests, a truly agile IT department delivers new servers to its business clients anywhere in the network infrastructure with a very quick turnaround. VMM enables this agility by providing IT administrators with the ability to deploy virtual machines in a fraction of the time it would take to deploy a physical server. Through one console, VMM allows administrators to manage and monitor virtual machines and hosts to ensure they are meeting the needs of the corresponding business groups.
   Quick provisioning of new machines In response to new server requests, a truly agile IT department delivers new servers to its business clients anywhere in the network infrastructure with a very quick turnaround. VMM enables this agility by providing IT administrators with the ability to deploy virtual machines in a fraction of the time it would take to deploy a physical server. Through one console, VMM allows administrators to manage and monitor virtual machines and hosts to ensure they are meeting the needs of the corresponding business groups.vQuick provisioning of new machines In response to new server requests, a truly agile IT department delivers new servers to its business clients anywhere in the network infrastructure with a very quick turnaround. VMM enables this agility by providing IT administrators with the ability to deploy virtual machines in a fraction of the time it would take to deploy a physical server. Through one console, VMM allows administrators to manage and monitor virtual machines and hosts to ensure they are meeting the needs of the corresponding business groups.
   Quick provisioning of new machines In response to new server requests, a truly agile IT department delivers new servers to its business clients anywhere in the network infrastructure with a very quick turnaround. VMM enables this agility by providing IT administrators with the ability to deploy virtual machines in a fraction of the time it would take to deploy a physical server. Through one console, VMM allows administrators to manage and monitor virtual machines and hosts to ensure they are meeting the needs of the corresponding business groups.
7. Intelligent Placement minimizes virtual machine guesswork in deployment VMM does extensive data analysis on a number of factors before recommending which physical server should host a given virtual workload. This is especially critical when administrators are determining how to place several virtual workloads on the same host machine. With access to historical data—provided by Operations Manager 2007—the Intelligent Placement process is able to factor in past performance characteristics to ensure the best possible match between the virtual machine and its host hardware.
8. Delegated virtual machine management for Development and Test Virtual infrastructures are commonly used in Test and Development environments, where there is constant provisioning and tear down of virtual machines for testing purposes. This latest version of VMM features a thoroughly reworked and improved self-service Web portal, through which administrators can delegate this provisioning role to authorized users while maintaining precise control over the management of virtual machines.
9. The library helps keep virtual machine components organized To keep a data center’s virtual house in order, VMM provides a centralized library to store various virtual machine “building blocks”—off-line machines and other virtualization components. With the library’s easy-to-use structured format, IT administrators can quickly find and reuse specific components, thus remaining highly productive and responsive to new server requests and modifications.
10. Windows PowerShell provides rich management and scripting environment The entire VMM application is built on the command-line and scripting environment, Windows PowerShell. This version of VMM adds additional PowerShell commandlets and “view script” controls, which allow administrators to exploit customizing or automating operations at an unprecedented level.

• Examples

Zones are not virtual machines, but an example of "operating-system virtualization". This includes other "virtual environments" (also called "virtual servers") such as Virtuozzo, FreeBSD Jails, Linux-VServer, chroot jail, and OpenVZ. These provide some form of encapsulation of processes within an operating system. These technologies have the advantages of being more resource-efficient than full virtualization and having better observability into multiple guests simultaneously; the disadvantage is that, generally, they can only run a single operating system and a single version/patch level of that operating system - so, for example, they cannot be used to run two applications, one of which only supports a newer OS version and the other only supporting an older OS version on the same hardware. However, Sun Microsystems has enhanced Solaris Zones to allow some zones to behave like Solaris 8 or Solaris 9 systems by adding a system call translator.