Oracle VM, Руководство пользователя

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Introduction to Virtualization 1-1
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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:
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What is Virtualization?
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Why Virtualize?
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Xen™ Technology
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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:
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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.
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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