Information Technology Reference
In-Depth Information
the document by submitting the address. Duplicates of documents are saved
only once under the same address, leading to reduced storage requirements.
Centera then retrieves the document regardless of where it may be physi-
cally located. EMC's Centera product takes the sensible approach that no one
can afford the risk of placing all of their data in one place, so the data are
distributed around the globe. Their cloud will monitor data usage and auto-
matically move data around in order to load-balance data requests and better
manage the flow of Internet traffic. Centera is constantly self-tuning to react
automatically to surges in demand. The Centera architecture functions as a
cluster that automatically configures itself upon installation. The system also
handles failover, load balancing, and failure notification.
1.2.2 Server Virtualization
Virtualization is a method of running multiple independent virtual operating
systems on a single physical computer. This approach maximizes the return
on investment for the computer. The term was coined in the 1960s in refer-
ence to a virtual machine (sometimes called a pseudo-machine). The creation
and management of virtual machines has often been called platform virtual-
ization . Platform virtualization is performed on a given computer (hardware
platform) by software called a control program. The control program creates
a simulated environment, a virtual computer, which enables the device to
use hosted software specific to the virtual environment, sometimes called
guest software.
The guest software, which is often itself a complete operating system,
runs just as if it were installed on a stand-alone computer. Frequently,
more than one virtual machine is able to be simulated on a single physical
computer, their number being limited only by the host device's physical
hardware resources. Because the guest software often requires access to
specific peripheral devices in order to function, the virtualized platform
must support guest interfaces to those devices. Examples of such devices
are the hard disk drive, CD-ROM, DVD, and network interface card.
Virtualization technology is a way of reducing the majority of hardware
acquisition and maintenance costs, which can result in significant savings
for any company.
1.3 Computer Hardware
The mechanical loom invented by a Frenchman named Joseph Jacquard
was an invention that made a profound impact on the history of indus-
trialization, as well as in the history of computing. With the use of cards
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