NxTop Terminology - Support & Tutorials | IDV Virtual Computer

NxTop Terminology

The terms defined below are either uncommon or have a particular meaning when pertaining to paravirtualization or to a NxTop solution in particular.

**NxTop Special Terms**
Base Image	The base image is the part of the NxTop image that contains the installed guest OS. Policy and Virtual Application assignments are not part of the base image, and changes to assignments do not change the base image. A NxTop only needs to be republished when the base image is updated. See NxTop image for more information.
Clone	A clone is a full copy of an existing virtual machine, resulting in an independent, separate virtual machine. The clone of a NxTop includes the base image (with any updates merged together) and any assigned policies or virtual applications.
Differencing Disk	A differencing disk stores a (child) record of all changes made to a parent disk and provides a way to save changes without altering the parent disk. The NxTop solution uses several differencing disks: An OS differencing disk to track changes to a NxTop's operating system during a session; the changes are used during the user session; the differencing disk is discarded after use on a shared NxTop, and retained after use for a custom NxTop. A user differencing disk to track changes to a user's files on a NxTop during a session; these are used to create incremental backups for a NxTop. Changes to the base image of a NxTop added during subsequent Publish actions are stored as a differencing disk. When an updated shared NxTop is distributed, only the differencing disk needs to be downloaded and added to the existing image.
Guest Operating System	A guest operating system is an operating system that runs on a virtual machine. In a virtualized system, a single computer can run more than one guest OS at the same time. The operating system (Windows, Linux, etc) installed on a NxTop image is an example of guest OS.
Hypervisor	Also called virtual machine monitor. A program that allows running several instances of one or of several different operating systems. The hypervisor is processor-specific. It manages and allocates all hardware resources and provides every guest operating system instance with the required resources. There are two types of hypervisor: Type 1 or "bare metal" hypervisors interact directly with the computer's hardware. They do not need a native OS. NxTop Engine is a Type 1 hypervisor. Type 2 hypervisors provide an emulation layer between a guest OS and the native OS, which interacts with the computer's hardware.
ISO file	An ISO file is an disk image of a software (operating system or application) installation kit. When run or opened, it installs the software just as installation from a CD or DVD.
NxTop Center	NxTop Center is the software that is installed on a Windows 2008 Server and used to create, maintain, administer and execute NxTops. The NxTop Center communicates over a network to the NxTop Engines running on computers, sending updated NxTops and other data, and receiving back-ups from the NxTops in use. It provides a user interface through a web browser.
NxTop Engine	NxTop Engine is a Type 1 (bare metal) hypervisor and management control framework that is installed and runs on computers (laptops or desktops) supporting x86 instruction set. The NxTop Engine manages and provisions the execution of NxTops as virtual machines on a computer, and communicates with the NxTop Center to receive updates and to send status and back-ups.
NxTop image	A NxTop image (NxTop) is a virtual machine, any assigned virtualized applications, and operating policies. The instance assigned to a user includes that user's data.
Snapback	Snapback is a description of the system drive on a NxTop discarding changes wrought during a user session. After a user session, the system drive "snaps back" to its initial condition, discarding any changes that occurred during the session.
Virtual Machine	A Virtual Machine (VM) is a virtualized representation of an installed operating system. Once started, the VM acts like an installed operating system. Also called a VHD (Virtual Hard Drive).
Virtualized Application	A virtualized application is an application that has been encapsulated, isolating it from the underlying operating system. A virtualized application is not installed in the traditional sense, although it operates as if it was. In NxTop, virtualized applications are assigned to a NxTop; the NxTop does not have to be re-published to include the virtualized application. When assigned or upgraded, the virtualized application is downloaded by the user's NxTop Engine, and made available when the user next starts the NxTop. Equally, if the virtualized is unassigned, it is removed without requiring any other change to the NxTop. NxTop does not include tools for producing virtualized applications, but supports applications virtualized using other tools, Altiris and Xenocode in particular.