Cloudware Technologies - Guide to Cloud Computing for Business and Technology Managers - page 299

15
Cloudware Technologies
Virtualization is widely used to deliver customizable computing environ-
ments on demand. Virtualization technology is one of the fundamental com-
ponents of cloud computing. Virtualization allows the creation of a secure,
customizable, and isolated execution environment for running applications
without affecting other users' applications. The basis of this technology
is the ability of a computer program—or a combination of software and
hardware—to emulate an executing environment separate from the one that
hosts such programs. For instance, we can run Windows OS on top of a vir-
tual machine, which itself is running on Linux OS. Virtualization provides
a great opportunity to build elastically scalable systems that can provision
additional capability with minimum costs.
15.1 Virtualization
Resource virtualization is at the heart of most cloud architectures. The
concept of virtualization allows an abstract, logical view on the physi-
cal resources and includes servers, data stores, networks, and software.
The basic idea is to pool physical resources and manage them as a whole.
Individual requests can then be served as required from these resource
pools. For instance, it is possible to dynamically generate a certain platform
for a specific application at the very moment when it is needed—instead of a
real machine, a virtual machine is instituted.
Resource management grows increasingly complex as the scale of a sys-
tem as well as the number of users and the diversity of applications using
the system increase. Resource management for a community of users with
a wide range of applications running under different operating systems is a
very difficult problem. Resource management becomes even more complex
when resources are oversubscribed and users are uncooperative. In addi-
tion to external factors, resource management is affected by internal factors,
such as the heterogeneity of the hardware and software systems, the ability
to approximate the global state of the system and to redistribute the load,
and the failure rates of different components. The traditional solution for
these in a data center is to install standard operating systems on individual
systems and rely on conventional OS techniques to ensure resource sharing,
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