Environmental Engineering Reference
In-Depth Information
PCs onto secure, cost-efficient virtualized
network resources, replacing PCs with
virtualized thin-client computers (Moore,
2006).
•
Virtualization is provided by software that
is installed on the host or on all application
hosts,
•
The virtualization engine is an out-of-band
solution, that passes the virtual volume de-
scriptions to the application hosts,
Storage virtualization automates tedious and
extremely time-consuming storage administra-
tion tasks. This means the storage administrator
can perform the tasks of backup, archiving, and
recovery more easily and in less time. Storage
virtualization is commonly used in file systems,
storage area networks (SANs), switches and vir-
tual tape systems. Users can implement storage
virtualization with software, hybrid hardware
or software appliances. Storage virtualization
provides many advantages. It is the pooling of
multiple physical storage resources into single
storage resource that is centrally managed. So
it is a way to reduce complexity of resources
management. The second advantage is that it
automates many time-consuming tasks. Consider-
ing the scarcity of trained storage personnel, this
advantage becomes increasingly important as IT
business grows. Third, the storage virtualization
can be used to hide the overall complexity of IT
infrastructure. Server virtualization can help to
provide standard enterprise environment across
the organizations desktops. Virtual servers com-
bine deployment software with preconfigured
deployment, making it easier to introduce new
services and applications, faster and easier than if
they are rolled out conventionally. It is possible to
move legacy systems from an old server to a new
server, which will consume less energy and help
to save costs. While ideally it seems that having
one virtualized server will reduce both energy
and hardware costs, one should be cautious in
consolidating servers since it may run the risk of
losing everything in case the server fails (Garg
et al.
, 2010).
End users have four choices for control the
virtualization architecture:
•
The virtualization engine is an in-band so-
lution located in the data path so that every
request travels through that device,
•
Virtualization is provided in the storage ar-
chitecture by switches and array controller
microcode (Tomic & Markic, 2010).
Virtualization supports cost savings by reduc-
ing hardware. By consolidating servers, reducing
down time and improving application performance
and freeing up critical resources, virtualization
helps to save up to 80% of running costs (Garg
et al.
, 2010).
The most spectacular achievements of IT
resources virtualization have been noticed in
VMware. The VMware technologies enable data
centers' decrease of electricity consumption by
70-80% and provide a flexible computing environ-
ment with much additional operational efficiency,
including business continuity, rapid provisioning
and automation, and standardized operating pro-
cedures (Poniatowski, 2010). Now, with VMware
vSphere 4.0 the 100% virtual data center is capable
of handling the most mission-critical workloads on
virtual machines. Usually, 30-40 virtual machines
are found on a single multicore server. VMware
is considered as the clear leader in virtual server
software selection. According to Forrester Re-
search Inc. survey 98% of respondents indicating
that they have ESX in their environment, 17% of
respondents state that they use either Microsoft
Virtual Server 2005 or Hyper-V, closely followed
by Citrix's Xen Server at 10%. Respondents no-
ticed the benefits in a virtual server environment
i.e. 23% of respondents ranked performance, 19%
named backup success, and 14% named capacity
efficiency (Poniatowski, 2010).
