Information Technology Reference
In-Depth Information
Citrix XenServer
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VMware ESX
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Microsoft Windows Server 2008 Hyper-V
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Red Hat Enterprise Virtualization (Kernel-Based Virtual Machine [KVM])
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Oracle provides a central point of reference for support of Solaris in the Hardware
This section provides a quick description of the HCL and then discusses Type 1
hypervisors, including those based on the Xen open-source project.
The HCL identifies hardware, servers, desktops, laptops, and a selection of pe-
ripherals that are compatible with Oracle Solaris and OpenSolaris releases; it also
provides information about available software support. The December 2009 HCL
section on virtualization is the reference point for this chapter.
All of the virtualization technologies listed earlier are Type 1—that is, “bare
metal”—hypervisors and are classified by each vendor as operating at the enter-
prise level. A virtual machine monitor (VMM) or hypervisor is a host program
that allows a single computer to support multiple execution environments. Users
see their virtual machines as self-contained computers isolated from other users,
even though every user is served by the same physical machine. A Type 1 hypervi-
sor runs directly on the hardware platform and sits between the guest operating
system in the virtual machine and the host computer's hardware. The primary
function of the hypervisor is to monitor and prevent a guest operating system
from accessing resources outside its privilege scope. Multiple virtual machines
can be run on a single physical system. Each virtual machine (known as a
guest
domain
) runs its own complete and distinct operating environment with its own
I/O devices, CPUs, memory, and network interfaces. Thus the hypervisor enables
the transparent sharing and partitioning of system resources.
As of December 2009, the majority of Type 1 hypervisors were 64-bit rather
than 32-bit based. A 32-bit hypervisor can access up to 4 GB of memory. However,
using Physical Address Extensions (PAE), it becomes possible to access as much
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