Environmental Engineering Reference
In-Depth Information
mainframe computer (Cala & Zielinski, 2007).
The fundamental idea behind virtualization is to
introduce an additional layer of indirection in ac-
cessing resources so that a lower-level resource can
be transparently mapped to multiple higher-level
resources or vice versa. Each level has its own
virtualization control layer which is responsible
for management and enforcement of mapping
between level n and n+1 of virtualized resources.
So virtualization decision may be performed
during the system configuration phase or even
in the run-time. The lowest layer of the hierarchy
represents physical resources. The virtualization of
resources is a powerful tool for creating advanced
data network services. A major advantage of the
virtualization of network functionality through
abstraction techniques is increased flexibility in
service creation, provisioning and differentiation.
The main purpose of the infrastructure-level
virtualization is to provide an abstracted view of a
collection of discrete computer, data, application,
network and storage resources for the purpose
of hiding complexity and improving flexibility
and productivity. An important beginning to the
virtualization process is to recognize that series
of components could be better managed if they
are abstracted. As these abstractions are crafted
in an appropriate and ultimately productive man-
ner, the predominant interactions remain with the
individual components. In this way, virtualization
also provides both an opportunity and the means
to abstract away complexity. It offers customers
the opportunity to build more efficient IT infra-
structures. Virtualization is seen as a step on the
road to utility computing. With virtualization, the
logical functions of the server, storage and network
elements are separated from their physical func-
tions (e.g. processor, memory, controllers, disks
and switches). In other words, all servers, stor-
age and network devices can be aggregated into
independent pools of resources. Elements from
these pools can then be allocated, provisioned, and
managed, manually or automatically, to meet the
changing needs and priorities of one's business
(Minoli, 2005).
BACKGROUND - INFORMATION
TECHNOLOGY INFRASTRUCTURE
VIRTUALIZATION
Virtualization is a broad term encompassing a set
of several deployment and management features
and could be defined as a technique used to abstract
the physical characteristics of the resources of a
system from other systems, applications or users
interacting with those resources (IBM, 2008).
The virtualization can make a single physical re-
source appear to be multiple logical resources, or
multiple physical resources appear to be a single
logical resource.
Virtualization is viewed as:
•
File virtualization: multiple files aggregat-
ed into a large file, presents integrated file
interface,
•
Software virtualization: enabling users to
use more-efficient, high-performance hard-
ware to support hundreds of applications
and several operating systems in a single
system. Applications are used in data path,
or in “plug-and-play” way from host view,
•
Desktop virtualization: providing the ac-
cess from anywhere for convenience and
to ensure business continuity and disaster
recovery,
•
Workstation virtualization: enabling the
centralized control of data and the efficient
administration of them among multiple us-
ers in different locations,
•
Storage virtualization: enabling users to
centralize data storage to protect data, im-
prove security and disaster recovery, and
accelerate data backups, while desktop vir-
tualization enables moving of data, appli-
cations, and processing away from desktop
