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Oracle® VM Server User's Guide
Release 2.1

Part Number E10898-04
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A configurable set of resources, including memory, virtual CPUs, network devices and disk devices, in which virtual machines run. A domain is granted virtual resources and can be started, stopped and restarted independently.

See also dom0 and domU.


An abbreviation for domain zero. The management domain with privileged access to the hardware and device drivers. Dom0 is the first domain started by the Oracle VM Server at boot time. Dom0 has more privileges than domU. It can access the hardware directly and can manage the device drivers for other domains. It can also start new domains.


An unprivileged domain with no direct access to the hardware or device drivers. Each domU is started by Oracle VM Server in dom0. The xm command-line tool is used to interact with each domU.


A guest operating system that runs within a domain in Oracle VM Server. A guest may be paravirtualized or hardware virtualized. Multiple guests can run on the same Oracle VM Server.

Hardware virtualized machine

A virtual machine with an unmodified guest operating system. It is not recompiled for the virtual environment. There may be substantial performance penalties running as a hardware virtualized guest. Enables Microsoft Windows™ operating system to be run, and legacy operating systems. Hardware virtualization is only available on Intel VT or AMD SVM CPUs.

Host computer

The physical computer on which Oracle VM Server is installed.


The hypervisor, monitor, or Virtual Machine Manager (VMM). It is the only fully privileged entity in the system. It controls only the most basic resources of the system, including CPU and memory usage, privilege checks, and hardware interrupts.

Management domain

See dom0.

Oracle VM Agent

An application installed with Oracle VM Server. It communicates with Oracle VM Manager for management of virtual machines. Oracle VM Manager manages the virtual machines running on Oracle VM Server by communicating with Oracle VM Agent. It contains three components: Server Pool Master, Utility Server, and Virtual Machine Server.

Oracle VM Server

A self-contained virtualization environment designed to provide a lightweight, secure, server-based platform for running virtual machines. Oracle VM Server is based upon an updated version of the Xen hypervisor technology. Includes Oracle VM Agent to enable communication with Oracle VM Manager.

Oracle VM Manager

Provides the user interface, which is a standard ADF (Application Development Framework) web application, to manage Oracle VM Server pools. Manages virtual machine lifecycle, including creating virtual machines from templates or from installation media, deleting, powering off, uploading, deployment and live migration of virtual machines. Manages resources including ISO files, templates and shared virtual disks. Also provides an API via a web service to Oracle VM Server.

Paravirtualized machine

A virtual machine with a kernel that is recompiled to be made aware of the virtual environment. Runs at near native speed, with memory, disk and network access optimized for maximum performance.

Preferred Server

A Virtual Machine Server that provides resources such as memory, CPU, network interface cards (NICs), and disk to the virtual machine. If you select only one Virtual Machine Server as the preferred server, the virtual machine always starts from and runs on this server. If you select multiple preferred servers, each time the virtual machine starts, it runs on the machine with the maximum available resources.


Also referred to as qemu-dm, which is the process name. The virtualization process which allows full virtualization of a PC system within another PC system.

Server Pool

Logically an autonomous region that contains one or more physical Oracle VM Servers. Presents a unified view of the storage where the virtual machines reside, and groups the users of these virtual machines into a single community called a group, in which each user is a server pool member.

Server Pool Master

A component of Oracle VM Agent. An application that acts as the contact point to Oracle VM Manager, and to other Oracle VM Agents. Provides virtual machine host load-balancing, and local persistency for Oracle VM Server.

There is only one Server Pool Master in a server pool. A physical server can perform as the Server Pool Master, Utility Server and Virtual Machine Server simultaneously.

Utility Server

A component of Oracle VM Agent. An application that handles I/O intensive operations for virtual machines, server pools and servers, for example, copying, moving and renaming files.

There can be more than one Utility Server in a server pool. A physical server can perform as the Server Pool Master, Utility Server and Virtual Machine Server simultaneously.


A virtual network interface for bridging network interfaces between domUs and dom0. When a domU is started it is assigned a number. This number is used to bridge the network interface from ethn to vifn.0.

Virtual disk

A file or set of files, usually on the host file system although it may also be a remote file system, that appears as a physical disk drive to the guest operating system.

Virtual Machine (VM)

A guest operating system and the associated application software that runs within Oracle VM Server. May be paravirtualized or hardware virtualized machines. Multiple virtual machines can run on the same Oracle VM Server.

Virtual Machine Manager (VMM)

See Hypervisor.

Virtual Machine Server

A component of Oracle VM Agent. An application which runs Oracle VM Server virtual machines. It can start and stop virtual machines, and collect performance data for the host and guest operating systems. Enables communication between the Server Pool Master, Utility Server and Virtual Machine Servers.

There can be more than one Virtual Machine Server in a server pool. A physical server can perform as the Server Pool Master, Utility Server and Virtual Machine Server simultaneously.

Virtual Machine Template

A template of a virtual machine. Contains basic configuration information such as the number of CPUs, memory size, hard disk size, and network interface card (NIC). Create virtual machines based on a virtual machine template using Oracle VM Manager.


See Virtual Machine Manager (VMM).


The Xen hypervisor is a small, lightweight, software virtual machine monitor, for x86-compatible computers. The Xen hypervisor securely executes multiple virtual machines on one physical system. Each virtual machine has its own guest operating system with almost native performance. The Xen hypervisor was originally created by researchers at Cambridge University, and derived from work done on the Linux kernel.