Choosing a Virtualization Technology - Oracle Solaris 10 System Virtualization Essentials - page 232

The Logical Domains' exclusive CPU assignment eliminates the need to
time-slice guest environments onto CPUs, avoiding the performance penalty
seen in other hypervisors.

A large number of completely separate Oracle Solaris instances.
Each domain can have its own patch levels and maintenance windows with-
out conflict or interference with other domains. This approach compares fa-
vorably to most OS virtualization (OSV) configurations, which may require
keeping patch levels synchronized across some or all guests.

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High resource granularity. Logical Domains permit fine-grained assign-
ment of CPU threads and RAM. Granularity is more flexible than with hard-
ware partitions but not as good as with OS virtualization.

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No extra license fees needed. This technology is included with all SPARC
CMT systems. Some hypervisors require a fee for use or support in addition
to acquisition and support fees for the operating systems and hardware.

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Excellent support for business agility and operational efficiencies.
The advanced features of Logical Domains, such as domain cloning and mo-
bility, support both flexibility and cost-effectiveness.

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Logical Domains have proven to be one of the most popular features of the CMT
server product line, with rapid uptake in adoption and feature growth occurring
since their introduction. This technology is widely used for server consolidation,
especially when replacing multiple small, horizontally scaled servers from previ-
ous SPARC product families.

7.1.3 x86 Hypervisors
The previously mentioned technologies support virtualized SPARC environments.
Oracle Solaris and OpenSolaris also run on the x86 platform on Intel and AMD
processors, and can run as guest virtual machines on a wide range of hypervi-
sors, including Oracle VM VirtualBox, Oracle VM Server for x86, VMware, xVM
hypervisor, and Microsoft's Hyper-V Server. This technology class provides the
following advantages:

Fault isolation. No software failure in virtual machine can affect another
domain, although a failure of the hypervisor may halt all of the VEs.

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Security isolation. A security penetration or compromise in one guest has
no effect on other guests. Given that most hypervisors are managed across
a network, however, this creates an opportunity for an intruder to access
a hypervisor directly; penetration of the hypervisor could theoretically give
access to each guest.

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