<s>
A	O
boot	B-Operating_System
image	I-Operating_System
is	O
a	O
type	O
of	O
disk	B-Application
image	I-Application
(	O
a	O
computer	O
file	O
containing	O
the	O
complete	O
contents	O
and	O
structure	O
of	O
a	O
storage	B-General_Concept
medium	I-General_Concept
)	O
.	O
</s>
<s>
When	O
it	O
is	O
transferred	O
onto	O
a	O
boot	B-Operating_System
device	O
it	O
allows	O
the	O
associated	O
hardware	O
to	O
boot	B-Operating_System
.	O
</s>
<s>
The	O
boot	B-Operating_System
image	I-Operating_System
usually	O
includes	O
the	O
operating	O
system	O
,	O
utilities	O
and	O
diagnostics	O
,	O
as	O
well	O
as	O
boot	B-Operating_System
and	O
data	O
recovery	O
information	O
.	O
</s>
<s>
A	O
specialized	O
image	O
for	O
a	O
particular	O
type	O
of	O
user	O
or	O
department	O
is	O
called	O
typically	O
a	O
departmental	B-Operating_System
boot	I-Operating_System
image	I-Operating_System
.	O
</s>
<s>
Building	O
such	O
an	O
image	O
can	O
take	O
days	O
or	O
weeks	O
,	O
and	O
involve	O
complex	O
decisions	O
about	O
licensing	O
and	O
permissions	O
-	O
including	O
which	O
passwords	O
to	O
store	O
in	O
the	O
boot	B-Operating_System
image	I-Operating_System
and	O
which	O
to	O
require	O
users	O
to	O
type	O
in	O
-	O
and	O
requires	O
experts	O
in	O
software	O
integration	O
to	O
do	O
.	O
</s>
<s>
However	O
,	O
once	O
built	O
,	O
the	O
boot	B-Operating_System
image	I-Operating_System
can	O
be	O
simply	O
copied	O
onto	O
devices	O
,	O
patched	O
within	O
reasonable	O
limits	O
,	O
and	O
remains	O
disposable	O
in	O
case	O
of	O
any	O
problems	O
(	O
viruses	O
in	O
particular	O
)	O
.	O
</s>
<s>
This	O
is	O
possible	O
because	O
unlike	O
other	O
hard	B-Device
drive	I-Device
images	O
(	O
which	O
may	O
contain	O
any	O
data	O
,	O
et	O
al	O
.	O
</s>
<s>
)	O
,	O
pure	O
boot	B-Operating_System
images	I-Operating_System
contain	O
no	O
mission-critical	O
data	O
.	O
</s>
<s>
By	O
definition	O
a	O
pure	O
boot	B-Operating_System
image	I-Operating_System
contains	O
no	O
data	O
that	O
cannot	O
be	O
reproduced	O
from	O
configurations	O
or	O
off-the-shelf	O
executables	O
.	O
</s>
<s>
In	O
particular	O
end-user	O
data	O
is	O
not	O
part	O
of	O
a	O
boot	B-Operating_System
image	I-Operating_System
,	O
although	O
some	O
operating	O
systems	O
require	O
that	O
a	O
copy	O
of	O
user	O
preferences	O
or	O
configuration	O
files	O
be	O
kept	O
within	O
the	O
boot	B-Operating_System
image	I-Operating_System
itself	O
,	O
e.g.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
registry	B-Protocol
.	O
</s>
<s>
Utilities	O
like	O
Norton	B-Application
Ghost	I-Application
keep	O
a	O
backup	O
copy	O
of	O
the	O
boot	B-Operating_System
image	I-Operating_System
,	O
for	O
quick	O
re-imaging	B-Operating_System
(	O
often	O
called	O
re-installation	B-Operating_System
)	O
in	O
the	O
event	O
of	O
a	O
problem	O
,	O
thus	O
avoiding	O
the	O
need	O
to	O
diagnose	O
a	O
specific	O
problem	O
with	O
a	O
specific	O
machine	O
.	O
</s>
<s>
Some	O
virtual	B-Architecture
machine	I-Architecture
infrastructure	O
can	O
directly	O
import	O
and	O
export	O
a	O
boot	B-Operating_System
image	I-Operating_System
for	O
direct	O
installation	O
to	O
"	O
bare	O
metal	O
"	O
,	O
i.e.	O
</s>
<s>
This	O
is	O
the	O
standard	O
technique	O
for	O
OEMs	O
to	O
install	O
identical	O
copies	O
of	O
an	O
operating	O
system	O
on	O
many	O
identical	O
machines	O
:	O
The	O
boot	B-Operating_System
image	I-Operating_System
is	O
created	O
as	O
a	O
virtual	B-Architecture
machine	I-Architecture
and	O
then	O
exported	O
,	O
or	O
created	O
on	O
one	O
disk	O
and	O
then	O
copied	O
via	O
a	O
boot	B-Operating_System
image	I-Operating_System
control	I-Operating_System
infrastructure	O
that	O
also	O
makes	O
virtual	B-Architecture
machine	I-Architecture
copies	O
.	O
</s>
<s>
The	O
VMware	O
vCenter	O
Converter	O
for	O
instance	O
lets	O
users	O
"	O
convert	O
physical	O
machines	O
to	O
virtual	B-Architecture
machines	I-Architecture
-	O
for	O
free	O
"	O
as	O
part	O
of	O
that	O
company	O
's	O
suite	O
of	O
products	O
to	O
make	O
images	O
easier	O
to	O
back	O
up	O
and	O
manage	O
.	O
</s>
<s>
Equivalents	O
exist	O
for	O
Xen	B-Operating_System
and	O
other	O
VM	O
systems	O
.	O
</s>
<s>
By	O
keeping	O
the	O
boot	B-Operating_System
image	I-Operating_System
entirely	O
separate	O
and	O
disposable	O
,	O
and	O
mandating	O
boot	B-Operating_System
image	I-Operating_System
control	I-Operating_System
,	O
organizations	O
seek	O
to	O
keep	O
their	O
total	O
cost	O
of	O
operations	O
(	O
including	O
its	O
total	O
cost	O
of	O
ownership	O
component	O
)	O
low	O
.	O
</s>
<s>
One	O
goal	O
of	O
boot	B-Operating_System
image	I-Operating_System
control	I-Operating_System
is	O
to	O
minimize	O
the	O
number	O
of	O
boot	B-Operating_System
images	I-Operating_System
used	O
by	O
an	O
organization	O
to	O
reduce	O
support	O
costs	O
.	O
</s>
<s>
Specifying	O
the	O
machine	O
hardware	O
to	O
minimize	O
unneeded	O
machine	O
diversity	O
and	O
minimize	O
the	O
resultant	O
number	O
of	O
boot	B-Operating_System
images	I-Operating_System
.	O
</s>
<s>
Organizing	O
the	O
network	O
so	O
that	O
boot	B-Operating_System
images	I-Operating_System
can	O
be	O
efficiently	O
supported	O
,	O
independent	O
of	O
data	O
.	O
</s>
<s>
Data	O
must	O
not	O
be	O
dependent	O
on	O
boot	B-Operating_System
devices	O
.	O
</s>
<s>
Hardware	O
acceptance	O
testing	O
on	O
each	O
new	O
machine	O
confirms	O
that	O
it	O
is	O
fit	O
for	O
use	O
in	O
a	O
standardized	O
boot	B-Operating_System
image	I-Operating_System
environment	O
.	O
</s>
<s>
Boot	B-Operating_System
image	I-Operating_System
installation	O
to	O
ensure	O
that	O
only	O
supportable	O
standardized	O
boot	B-Operating_System
images	I-Operating_System
are	O
used	O
.	O
</s>
<s>
Troubleshooting	O
and	O
help	O
desk	O
functions	O
employ	O
standardized	O
tests	O
to	O
identify	O
the	O
source	O
of	O
problems	O
:	O
boot	B-Operating_System
,	O
software	O
,	O
or	O
hardware	O
.	O
</s>
<s>
These	O
would	O
use	O
backup	O
copies	O
of	O
a	O
boot	B-Operating_System
image	I-Operating_System
created	O
with	O
utilities	O
such	O
as	O
Norton	B-Application
Ghost	I-Application
.	O
</s>
<s>
In	O
a	O
large	O
organization	O
with	O
many	O
compatible	O
machines	O
,	O
rapid	O
recovery	O
by	O
replacing	O
with	O
a	O
backup	O
boot	B-Operating_System
image	I-Operating_System
may	O
only	O
take	O
a	O
few	O
minutes	O
,	O
with	O
considerable	O
cost	O
savings	O
.	O
</s>
<s>
Installing	O
services	O
for	O
the	O
disabled	O
with	O
a	O
single	O
boot	B-Operating_System
image	I-Operating_System
in	O
a	O
manner	O
that	O
is	O
ubiquitous	O
and	O
cost	O
effective	O
,	O
meeting	O
the	O
needs	O
of	O
all	O
staff	O
regardless	O
of	O
disability	O
,	O
with	O
available	O
technology	O
services	O
.	O
</s>
<s>
Using	O
thin	B-Device
clients	I-Device
for	O
off-spec	O
machines	O
to	O
eliminate	O
the	O
need	O
for	O
special	O
boot	B-Operating_System
images	I-Operating_System
.	O
</s>
<s>
Many	O
organizations	O
use	O
thin	B-Device
clients	I-Device
for	O
applications	O
which	O
require	O
high	O
security	O
,	O
involve	O
unreliable	O
users	O
or	O
repurpose	O
older	O
machines	O
for	O
continued	O
use	O
.	O
</s>
<s>
A	O
cascading	O
strategy	O
involves	O
re-imaging	B-Operating_System
older	O
,	O
off-spec	O
machines	O
to	O
thin	B-Device
client	I-Device
boot	B-Operating_System
images	I-Operating_System
so	O
that	O
they	O
may	O
continue	O
in	O
use	O
for	O
some	O
less	O
demanding	O
or	O
more	O
access-controlled	O
applications	O
.	O
</s>
