Virtualization explained
Virtualization is a technology that makes it possible to
run multiple operating systems and multiple applications on the
same computer at the same time. In essence you can run several
different servers on the same physical box, therefore reducing the
need to purchase new hardware for each server.
How does virtualization work?
VMware virtualization inserts a thin layer of software directly
onto the computer hardware, known as a 'hypervisor'. The
hypervisor transforms or 'virtualizes' the hardware resources
of a computer (CPU, RAM etc) to create a fully functional 'virtual
machine' that can run its own operating system and applications
just like a 'real' computer.
More on virtual machines
A virtual machine is an isolated software 'container' that runs
its own operating system and applications as if it were a physical
computer. A virtual machine behaves exactly like a physical
computer and contains its own virtual (i.e., software based) CPU,
RAM, hard disk and network card.
The major benefit of virtual machines is
that there are no hardware-specific dependencies -
virtual machines are entirely software based. This means your
virtual server is not tied to the host hardware it is running on
and can easily be moved onto different physical hardware at any
time.
Operating systems such as Windows can't tell the difference
between a virtual machine and a physical machine, nor can
applications or other computers on a network.
Because virtual machines are only software based they offer a
number of major advantages over physical hardware:
Hardware independance
Virtual machines are completely independent from the physical
hardware they run on. A virtual machine can be configured with a
number of various virtual components (eg, CPU, network card, SCSI
controller) that are completely different from the physical
components that are present on the physical host machine. Virtual
machines on the same physical server can even run different kinds
of operating systems (Windows, Linux, etc).
A huge benefit to hardware independance is the ability to move a
virtual machine from one type of physical host to another without
making any changes to the device drivers, operating system, or
applications. With products such as VMware's vMotion, virtual
machines can be relocated onto different physical hosts wihile
still running. Users remain logged into the server and
websites running on the server continue to function. Hardware
independence also means that you can run a mixture of operating
systems such as Windows and Linux on the same single physical host,
reducing investment.
Isolation
While virtual machines can share the physical resources of a
single computer, they still remain completely isolated from each
other as if they were separate physical machines. If there are four
virtual machines on a single physical server and one of the virtual
machines crashes, the other three virtual machines remain
available. Isolation is an important reason why the availability
and security of applications running in a virtual environment is
far superior to applications running in a traditional, non
virtualized system.
Encapsulation
A virtual machine is essentially a software container that
bundles or "encapsulates" a complete set of virtual hardware
resources such as RAM or CPU, in additional to an operating system
and all its applications, inside a software package. Encapsulation
makes virtual machines incredibly portable and easy to manage. For
example, you can move and copy a virtual machine from one location
to another just like any other software file, or save a virtual
machine on any standard data storage medium, from a pocket-sized
USB flash memory card to an enterprise storage area networks
(SANs).
For more information on how virtualization can be implemented as a
cost-effective technology or as part of your Disaster Recovery
Plan contact
Jatech or call our team now on 01453 791909.
