1 Introduction to Virtualization
This Chapter provides introductory information on virtualization. It
discusses why you would want to use virtualization, the technology
provided, and features of Oracle VM. It contains the following sections:
What is Virtualization?
Why Virtualize?
Xen™ Technology
Oracle VM
1.1 What is Virtualization?
Virtualization is the ability to run multiple virtual machines on a single
piece of hardware. The hardware runs software which enables you to
install multiple operating systems which are able to run simultaneously
and independently, in their own secure environment, with minimal
reduction in performance. Each virtual machine has its own virtual CPU,
network interfaces, storage and operating system.
1.2 Why Virtualize?
With increased server provisioning in the datacenter, several factors play
a role in stifling growth. Increased power and cooling costs, physical space
constraints, man power and interconnection complexity all contribute
significantly to the cost and feasibility of continued expansion.
Commodity hardware manufacturers have begun to address some of
these concerns by shifting their design goals. Rather than focus solely on
raw gigahertz performance, manufacturers have enhanced the feature
sets of CPUs and chip sets to include lower wattage CPUs, multiple cores
per CPU die, advanced power management, and a range of virtualization
features. By employing appropriate software to enable these features,
several advantages are realized:
Server Consolidation: By combining workloads from a number of
physical hosts into a single host, a reduction in servers can be
achieved and a corresponding decrease in interconnect hardware.
Traditionally, these workloads would need to be specially crafted,
partially isolated and well behaved, but with new virtualization
techniques none of these requirements are necessary.
Reduction of Complexity: Infrastructure costs are massively
reduced by removing the need for physical hardware, and
networking. Instead of having a large number of physical
computers, all networked together, consuming power and
administration costs, fewer computers can be used to achieve the
same goal. Administration and physical setup is less time
consuming and costly.
Isolation: Virtual machines run in sand-boxed environments. Virtual
machines cannot access the resources of other virtual machines. If
one virtual machine performs poorly, or crashes, it does not affect
any other virtual machine.
Platform Uniformity: In a virtualized environment, a broad,
heterogeneous array of hardware components is distilled into a
uniform set of virtual devices presented to each guest operating
system. This reduces the impact across the IT organization: from
support, to documentation, to tools engineering.
Legacy Support: With traditional bare-metal operating system
installations, when the hardware vendor replaces a component of a
system, the operating system vendor is required to make a
corresponding change to enable the new hardware (for example, an
Ethernet card). As an operating system ages, the operating system
vendor may no longer provide hardware enabling updates. In a
virtualized operating system, the hardware remains constant for as
long as the virtual environment is in place, regardless of any
changes occurring in the real hardware, including full replacement.
1.3 Xen™ Technology
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.
The Xen hypervisor has been improved and included with Oracle VM
Server.
1.4 Oracle VM
Oracle VM is a platform that provides a fully equipped environment for
better leveraging the benefits of virtualization technology. Oracle VM
enables you to deploy operating systems and application software within
a supported virtualization environment. The components of Oracle VM are:
Oracle VM Manager: Provides the user interface, which is a
standard ADF (Application Development Framework) web
application, to manage Oracle VM Servers, virtual machines, and
resources. Use Oracle VM Manager to:
o Create virtual machines
o Create server pools
o Power on and off virtual machines
o Pause and unpause live virtual machines
o Deploy virtual machines
o Manage virtual NICs (Network Interface Cards), disks and
shared disks
o Create virtual machine templates from virtual machines
o Import virtual machines and templates
o Manage high availability of Oracle VM Servers, server pools,
and guest virtual machines
o Perform live migration of virtual machines
o Import and manage ISOs
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 underlying Xen hypervisor technology, and
includes Oracle VM Agent.
Oracle VM Agent: Installed with Oracle VM Server. Oracle VM
Manager communicates with Oracle VM Agent to manage the Oracle
VM Servers and virtual machines running on it.
Figure 1-1, "Oracle VM Architecture" shows the components of Oracle VM.
Figure 1-1 Oracle VM Architecture
Description of "Figure 1-1 Oracle VM Architecture"
This book discusses Oracle VM Server, and the Oracle VM Agent. See
the Oracle VM Manager Installation Guide and the Oracle VM Manager
User's Guide for information on installing, and using Oracle VM Manager,
and managing Oracle VM Servers.
