Novell ZENWORKS APPLICATION VIRTUALIZATION 8.0.1 - 8-20-2010 User Manual page 9

2.4 H
OW IS
HARDWARE VIRTUALIZATION
Unlike hardware virtualization systems such as Microsoft Virtual PC and VMware, the Novell
application virtualization system virtualizes only those operating system features required for
application execution. This allows virtualized applications to operate extremely efficiently, with
essentially the same performance characteristics as native executables.
Advantages of Novell virtualization over hardware virtualization include:
•
Optimal performance: Novell virtual apps execute at essentially the same speed as
applications running natively against the host hardware, with only a small additional
memory footprint. By contrast, applications running within hardware-virtualized
environments experience significant slowdowns and impose a large memory footprint
because the virtual machine must include an entire virtualized host operating system.
•
Dramatically reduced application size: Novell virtual apps require a disk footprint
proportional only to the size of the virtualized application, data, and included
components. As a result, Novell virtual apps are typically small enough to be
conveniently and quickly downloaded by end-users. Hardware virtualization requires
an entire host operating system image, including many basic subsystems that are already
present on the end-user device. Each virtual machine may occupy several gigabytes of
storage.
•
Ability to run multiple virtual applications: Because of low-overhead characteristics, it is
possible to run multiple simultaneous virtual environments per processor. Conversely,
due to the high overhead of hardware virtualization, only a very small number of
hardware-virtualized environments per processor can be run.
•
Reduced licensing costs: Novell does not require the purchase of separate operating
system licenses to use a virtual application. Hardware virtualization systems require a
host operating system in order function, possibly imposing additional licensing costs and
restrictions.
Hardware virtualization may be appropriate in certain specialized scenarios, including:
•
Non-Windows operating systems: Novell virtual apps run only on the Windows operating
system. Hardware virtualization can execute any operating system compatible with the
underlying virtualized hardware, such as Linux.
•
Kernel mode virtualization: The Novell Virtual OS only virtualizes user-mode operating
system features, whereas hardware virtualization systems emulate the entire OS stack,
including kernel mode components. Applications requiring device drivers or other non-
user-mode software may require a hardware-virtualized environment to function
properly.
You should carefully evaluate the advantages and disadvantages of different virtualization
approaches before deciding on a technology to adopt for your deployment scenario.
11
N
OVELL VIRTUALIZATION DIFFERENT FROM
?
Novell ZENworks Application Virtualization