Glossary of Virtualization (and Computing) Terms

Version 11

    Disclaimer: This is a personal document and is not official or endorsed by VMware. Feedback, suggestions, and edits are welcome.


    This document is intended for someone new to virtualization or who needs  to understand the terminology used when discussing virtualization.  Other links of interest include

    A Beginner's Guide to VMware Fusion and

    Frequently Asked Questions about VMware Fusion. Note: This glossary of virtualization is aimed towards x86, VMware, and specifically Fusion.



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    Term Meaning
    ACEA VMware product that provides a way to secure and manage virtual  machines, for example in the workplace. The proper name is "VMware ACE".
    AMD-VAMD's implementation of virtualization hardware assist
    Binary TranslationA virtualization technique pioneered by VMware in the late '90s for the  x86 architecture where the instruction stream is inspected and  non-virtualizable machine instructions are replaced with "safe" code.  Contrast with hardware assist.
    Boot Camp virtual machineUsing an existing Boot Camp installation as a virtual machine. Contrast with normal virtual machine.
    console windowThe window on the host which allows you to interact with the guest. Note: Not really applicable to a Unity situation, this is mainly single-window mode.
    ConverterA VMware product that converts a physical (or virtual) Windows machine  to a virtual machine. The proper name is "VMware Converter".
    coreComputational unit. There may be multiple cores in a socket. Note this is a generic term, not to be confused with Intel's Core (Solo, Duo, etc.) product line.
    COW diskCopy-On-Write disk. Part of a snapshot, and keeps track of disk changes since the snapshot was taken.
    CPUCentral Processing Unit. Depending on context, might refer to a core or a socket.
    ESXiA free VMware virtualization software product aimed at businesses and  enterprise. Unlike Player/Fusion/Workstation/Server, does not run on top  of another OS. The proper name is "VMware ESXi".
    file-based diskA virtual disk where the contents are stored in a file  (or multiple files, for split disks). Contrast with raw disk.
    FusionA VMware hosted virtualization software product. Runs on Mac OS X hosts. The proper name is "VMware Fusion".
    fullscreenA view mode where the guest display takes up an entire physical monitor (or more). Contrast with single-window and Unity.
    guestThe operating system that runs in a virtual machine. There can be  multiple guests per physical machine, but only one per virtual machine.  Contrast with host.
    grabTo direct input (i.e. keyboard and mouse) to a virtual machine, for example by clicking in a console window. Contrast with ungrab.
    hard ungrabForced ungrab, such as by pressing ctrl-cmd (by default) in Fusion.
    hardware assistA virtualization technique where the CPU allows software to specify  instructions (e.g. non-virtualizable ones) to cause traps (thus making  them virtualizable). Examples on the x86 architecture include VT-x and AMD-V. Contrast with Binary Translation.
    hostThe OS that has direct control of the hardware. There is only one host  per physical machine. What the virtualization software runs on; e.g. for  Fusion, the host is OS X. Contrast with guest.
    HGFSAbbreviation for "Host-Guest File System". VMware's name for the guest-visible aspect of a Shared Folder.
    hypervisorSoftware that controls virtual machines, managing resources and ensuring that guests are properly isolated.
    ImporterA companion program for Fusion 1.x that translates third-party virtual  machines (e.g. Parallels, VirtualPC) to a format that Fusion  understands. As of Fusion 2, this functionality is built in to Fusion.  The proper name is "VMware Importer".
    NICNetwork Interface Card. What a computer uses to talk to the network; can be wired or wireless.
    PlayerA free VMware hosted virtualization software product aimed at end  users. Has fewer features than Workstation or Fusion. Runs on Windows  and Linux hosts. The proper name is "VMware Player".
    pNICPhysical NIC; what the host uses to talk to the network.
    vNICVirtual NIC; what we present to a guest. Our vNICs always appear as wired devices to the guest, even if the pNIC is a wireless device.
    network shareA method for accessing one computer's filesystem from another computer;  not restricted to virtualization. Well-known examples include NFS and  SMB/CIFS. Does not require VMware Tools, but does require a network  connection. Contrast with Shared Folder.
    normal virtual machineFor example, what you get when you create a new virtual machine with  all defaults. A normal virtual machine is portable between computers. A  normal virtual machine does not have things such as raw disks.
    Operating SystemSoftware that controls the hardware and runs other programs. Well-known examples include Windows and OS X.
    OSAbbreviation for operating system.
    partitionnoun: A self-contained region of a hard disk that usually contains a filesystem.
    verb: to create a partition
    A partition is not the same as a virtual machine, nor do you have to partition your Mac's hard drive to create a virtual machine.
    physical machineA computer that (for example) you could touch or throw out a window. Contrast with virtual machine.
    raw diskA virtual disk where the contents are stored directly on a partition on  the physical machine. Not safe to use with snapshots or suspending. For  example, a Boot Camp virtual machine uses a raw disk. Contrast with file-based disk.
    Shared FolderIn the context of VMware, a specific method for accessing the host filesystem from the guest using VMware Tools. Does not require a network connection. Contrast with network share.
    single windowA view mode where the guest's display appears in a single host window. This is the default view in Fusion. Contrast with Unity and fullscreen.
    SMPSymmetric MultiProcessing. Using multiple cores at once.
    vSMPVirtual Symmetric MultiProcessing. Using multiple cores in one virtual machine.
    snapshotA way to save all state (disk, RAM, CPU) of a virtual machine (note  this does not include network, since that is external). As long as you  don't delete the snapshot (or underlying base disks), you can return to  this state. Useful for testing purposes or for remembering a known-good  setup.
    socketA (physical) computational unit, e.g. something you would plug a CPU  into. A computer may have multiple sockets, a socket may have multiple cores.
    Can also refer to a particular type of communication method between programs.
    soft ungrabAutomatic ungrab, such as when your mouse leaves the console window.
    ToolsOptional software installed in the guest that improves performance and usability. The proper name is "VMware Tools".
    ungrabTo direct input (i.e. keyboard and mouse) away from a virtual machine. See also soft ungrab and hard ungrab. Contrast with grab.
    UnityA view mode where guest windows appear to be on the host, e.g. you can  interleave them with host windows. Requires VMware Tools; not available  for all guests. Contrast with single-window and fullscreen.
    virtual machineA "computer" that exists only in software. Contrast with physical machine.
    virtual machine monitorAnother name for a hypervisor.
    VMCommon abbreviation for virtual machine.
    VMwareCompany that makes virtualization (and related) software.
    VT-xIntel's implementation of virtualization hardware assist for x86. All Intel Macs have this.
    WorkstationA VMware hosted virtualization software product aimed at developers and  testers, with a number of features that Fusion does not have. Runs on  Windows and Linux hosts. The proper name is "VMware Workstation".