In computing, a virtual machine (VM) is the virtualization or emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two. Virtual machines differ and are organized by their function, shown here:
A disk image is a snapshot of a storage device's structure and data typically stored in one or more computer files on another storage device. Traditionally, disk images were bit-by-bit copies of every sector on a hard disk often created for digital forensic purposes, but it is now common to only copy allocated data to reduce storage space. Compression and deduplication are commonly used to reduce the size of the image file set. Disk imaging is done for a variety of purposes including digital forensics, cloud computing, system administration, as part of a backup strategy, and legacy emulation as part of a digital preservation strategy. Disk images can be made in a variety of formats depending on the purpose. Virtual disk images are intended to be used for cloud computing, ISO images are intended to emulate optical media and raw disk images are used for forensic purposes. Proprietary formats are typically used by disk imaging software. Despite the benefits of disk imaging the storage costs can be high, management can be difficult and they can be time consuming to create.
VMware, Inc. is an American cloud computing and virtualization technology company with headquarters in Palo Alto, California. VMware was the first commercially successful company to virtualize the x86 architecture.
Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic information about platform virtualization hypervisors.
Parallels Workstation is the first commercial software product released by Parallels, Inc., a developer of desktop and server virtualization software. The Workstation software consists of a virtual machine suite for Intel x86-compatible computers which allows the simultaneous creation and execution of multiple x86 virtual computers. The product is distributed as a download package. Parallels Workstation has been discontinued for Windows and Linux as of 2013.
In computing, thin provisioning involves using virtualization technology to give the appearance of having more physical resources than are actually available. If a system always has enough resource to simultaneously support all of the virtualized resources, then it is not thin provisioned. The term thin provisioning is applied to disk layer in this article, but could refer to an allocation scheme for any resource. For example, real memory in a computer is typically thin-provisioned to running tasks with some form of address translation technology doing the virtualization. Each task acts as if it has real memory allocated. The sum of the allocated virtual memory assigned to tasks typically exceeds the total of real memory.
A virtual appliance is a pre-configured virtual machine image, ready to run on a hypervisor; virtual appliances are a subset of the broader class of software appliances. Installation of a software appliance on a virtual machine and packaging that into an image creates a virtual appliance. Like software appliances, virtual appliances are intended to eliminate the installation, configuration and maintenance costs associated with running complex stacks of software.
VMware Workstation Pro is a hosted hypervisor that only runs on x64 versions of Windows and Linux operating systems. There used to be an x86-32 version for earlier versions for the software. It enables users to set up virtual machines (VMs) on a single physical machine and use them simultaneously along with the host machine. Each virtual machine can execute its own operating system, including versions of Microsoft Windows, Linux, BSD, and MS-DOS. VMware Workstation is developed and sold by VMware, Inc. There is a free-of-charge version called VMware Workstation Player, for non-commercial use. An operating systems license is needed to use proprietary ones such as Windows. Ready-made Linux VMs set up for different purposes are available from several sources.
VMware ESXi is an enterprise-class, type-1 hypervisor developed by VMware for deploying and serving virtual computers. As a type-1 hypervisor, ESXi is not a software application that is installed on an operating system (OS); instead, it includes and integrates vital OS components, such as a kernel.
VMware VMFS is VMware, Inc.'s clustered file system used by the company's flagship server virtualization suite, vSphere. It was developed to store virtual machine disk images, including snapshots. Multiple servers can read/write the same filesystem simultaneously while individual virtual machine files are locked. VMFS volumes can be logically "grown" by spanning multiple VMFS volumes together.
Oracle VM VirtualBox is a type-2 hypervisor for x86 virtualization developed by Oracle Corporation. VirtualBox was originally created by InnoTek Systemberatung GmbH, which was acquired by Sun Microsystems in 2008, which was in turn acquired by Oracle in 2010.
Infrastructure as a service (IaaS) is a cloud computing service model by means of which computing resources are supplied by a cloud services provider. The IaaS vendor provides the storage, network, servers, and virtualization (which mostly refers, in this case, to emulating computer hardware). This service enables users to free themselves from maintaining an on-premises data center. The IaaS provider is hosting these resources in either the public cloud (meaning users share the same hardware, storage, and network devices with other users), the private cloud (meaning users do not share these resources), or the hybrid cloud (combination of both).
VMware Infrastructure is a collection of virtualization products from VMware. Virtualization is an abstraction layer that decouples hardware from operating systems. The VMware Infrastructure suite allows enterprises to optimize and manage their IT infrastructure through virtualization as an integrated offering. The core product families are vSphere, vSAN and NSX for on-premises virtualization. VMware Cloud Foundation (VCF) is an infrastructure platform for hybrid cloud management. The VMware Infrastructure suite is designed to span a large range of deployment types to provide maximum flexibility and scalability.
Open Virtualization Format (OVF) is an open standard for packaging and distributing virtual appliances or, more generally, software to be run in virtual machines.
VHD and its successor VHDX are file formats representing a virtual hard disk drive (HDD). They may contain what is found on a physical HDD, such as disk partitions and a file system, which in turn can contain files and folders. They are typically used as the hard disk of a virtual machine, are built into modern versions of Windows, and are the native file format for Microsoft's hypervisor, Hyper-V.
The TurnKey Linux Virtual Appliance Library is a free open-source software project which develops a range of Debian-based pre-packaged server software appliances. Turnkey appliances can be deployed as a virtual machine, in cloud computing services such as Amazon Web Services or installed in physical computers.
libguestfs is a C library and a set of tools for accessing and modifying virtual disk images used in platform virtualization. The tools can be used for viewing and editing virtual machines (VMs) managed by libvirt and files inside VMs, scripting changes to VMs, creating VMs, and much else besides. It was created because of security issues, when virtual disk images are mounted directly on the host system.
SUSE Studio was an online Linux software creation tool by SUSE. Users could develop their own Linux distro, software appliance, or virtual appliance, mainly choosing which applications and packages they want on their "custom" Linux and how it looks.
In computer security, virtual machine escape is the process of a program breaking out of the virtual machine on which it is running and interacting with the host operating system. A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". In 2008, a vulnerability in VMware discovered by Core Security Technologies made VM escape possible on VMware Workstation 6.0.2 and 5.5.4. A fully working exploit labeled Cloudburst was developed by Immunity Inc. for Immunity CANVAS. Cloudburst was presented in Black Hat USA 2009.
Teradici Corporation was a privately held software company founded in 2004, which was acquired by HP Inc. in October 2021. Teradici initially developed a protocol (PCoIP) for compressing and decompressing images and sound when remotely accessing blade servers, and implemented it in hardware. This technology was later expanded to thin clients/zero clients for general Virtual Desktop Infrastructure. Teradici's protocol or hardware is used by HP, Dell-Wyse, Amulet Hotkey, Samsung, Amazon Web Services, Fujitsu, and VMware.
