<s>
Disaster	B-General_Concept
recovery	I-General_Concept
is	O
the	O
process	O
of	O
maintaining	O
or	O
reestablishing	O
vital	O
infrastructure	O
and	O
systems	O
following	O
a	O
natural	O
or	O
human-induced	O
disaster	O
,	O
such	O
as	O
a	O
storm	O
or	O
battle	O
.	O
</s>
<s>
Disaster	B-General_Concept
recovery	I-General_Concept
focuses	O
on	O
the	O
information	B-General_Concept
technology	I-General_Concept
(	O
IT	O
)	O
or	O
technology	O
systems	O
supporting	O
critical	O
business	O
functions	O
as	O
opposed	O
to	O
business	O
continuity	O
.	O
</s>
<s>
Disaster	B-General_Concept
recovery	I-General_Concept
assumes	O
that	O
the	O
primary	O
site	O
is	O
not	O
immediately	O
recoverable	O
and	O
restores	O
data	O
and	O
services	O
to	O
a	O
secondary	O
site	O
.	O
</s>
<s>
It	O
encompasses	O
IT	O
disaster	B-General_Concept
recovery	I-General_Concept
planning	O
and	O
wider	O
IT	O
resilience	O
planning	O
.	O
</s>
<s>
It	O
also	O
incorporates	O
IT	B-Application
infrastructure	I-Application
and	O
services	O
related	O
to	O
communications	O
,	O
such	O
as	O
telephony	O
and	O
data	O
communications	O
.	O
</s>
<s>
Planning	O
includes	O
arranging	O
for	O
backup	B-General_Concept
sites	I-General_Concept
,	O
whether	O
they	O
are	O
"	O
hot	O
"	O
(	O
operating	O
prior	O
to	O
a	O
disaster	O
)	O
,	O
"	O
warm	O
"	O
(	O
ready	O
to	O
begin	O
operating	O
)	O
,	O
or	O
"	O
cold	O
"	O
(	O
requires	O
substantial	O
work	O
to	O
begin	O
operating	O
)	O
,	O
and	O
standby	O
sites	O
with	O
hardware	O
as	O
needed	O
for	O
continuity	O
.	O
</s>
<s>
Recovery	O
Time	O
Actual	O
(	O
RTA	O
)	O
is	O
the	O
critical	O
metric	O
for	O
business	B-General_Concept
continuity	I-General_Concept
and	I-General_Concept
disaster	I-General_Concept
recovery	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
if	O
RPO	O
is	O
measured	O
in	O
minutes	O
,	O
then	O
in	O
practice	O
,	O
off-site	O
mirrored	O
backups	O
must	O
be	O
continuously	B-General_Concept
maintained	I-General_Concept
as	O
a	O
daily	O
off-site	O
backup	O
will	O
not	O
suffice	O
.	O
</s>
<s>
Planning	O
for	O
disaster	B-General_Concept
recovery	I-General_Concept
and	O
information	B-General_Concept
technology	I-General_Concept
(	O
IT	O
)	O
developed	O
in	O
the	O
mid	O
to	O
late	O
1970s	O
as	O
computer	O
center	O
managers	O
began	O
to	O
recognize	O
the	O
dependence	O
of	O
their	O
organizations	O
on	O
their	O
computer	O
systems	O
.	O
</s>
<s>
At	O
that	O
time	O
,	O
most	O
systems	O
were	O
batch-oriented	O
mainframes	B-Architecture
.	O
</s>
<s>
An	O
offsite	O
mainframe	B-Architecture
could	O
be	O
loaded	O
from	O
backup	O
tapes	O
pending	O
recovery	O
of	O
the	O
primary	O
site	O
;	O
downtime	O
was	O
relatively	O
less	O
critical	O
.	O
</s>
<s>
The	O
disaster	B-General_Concept
recovery	I-General_Concept
industry	O
developed	O
to	O
provide	O
backup	O
computer	O
centers	O
.	O
</s>
<s>
During	O
the	O
1980s	O
and	O
90s	O
,	O
computing	O
grew	O
exponentially	O
,	O
including	O
internal	O
corporate	O
timesharing	O
,	O
online	O
data	O
entry	O
and	O
real-time	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Availability	O
of	O
IT	B-General_Concept
systems	I-General_Concept
became	O
more	O
important	O
.	O
</s>
<s>
Regulatory	O
agencies	O
became	O
involved	O
;	O
availability	O
objectives	O
of	O
2	O
,	O
3	O
,	O
4	O
or	O
5	O
nines	O
(	O
99.999	O
%	O
)	O
were	O
often	O
mandated	O
,	O
and	O
high-availability	B-General_Concept
solutions	O
for	O
hot-site	B-General_Concept
facilities	O
were	O
sought	O
.	O
</s>
<s>
The	O
rise	O
of	O
cloud	B-Architecture
computing	I-Architecture
since	O
2010	O
created	O
new	O
opportunities	O
for	O
system	O
resiliency	O
.	O
</s>
<s>
Every	O
$1	O
spent	O
on	O
hazard	O
mitigation	O
(	O
such	O
as	O
a	O
disaster	B-General_Concept
recovery	I-General_Concept
plan	I-General_Concept
)	O
saves	O
society	O
$4	O
in	O
response	O
and	O
recovery	O
costs	O
.	O
</s>
<s>
As	O
IT	B-General_Concept
systems	I-General_Concept
have	O
become	O
increasingly	O
critical	O
to	O
the	O
smooth	O
operation	O
of	O
a	O
company	O
,	O
and	O
arguably	O
the	O
economy	O
as	O
a	O
whole	O
,	O
the	O
importance	O
of	O
ensuring	O
the	O
continued	O
operation	O
of	O
those	O
systems	O
,	O
and	O
their	O
rapid	O
recovery	O
,	O
has	O
increased	O
.	O
</s>
<s>
The	O
choice	O
of	O
mechanisms	O
is	O
reflected	O
in	O
a	O
disaster	B-General_Concept
recovery	I-General_Concept
plan	I-General_Concept
(	O
DRP	O
)	O
.	O
</s>
<s>
The	O
disaster	B-General_Concept
recovery	I-General_Concept
strategy	O
derives	O
from	O
the	O
business	O
continuity	O
plan	O
.	O
</s>
<s>
A	O
cost-benefit	O
analysis	O
highlighs	O
which	O
disaster	B-General_Concept
recovery	I-General_Concept
measures	O
are	O
appropriate	O
.	O
</s>
<s>
Disaster	B-General_Concept
recovery	I-General_Concept
as	O
a	O
service	O
(	O
DRaaS	O
)	O
is	O
an	O
arrangement	O
with	O
a	O
third	O
party	O
vendor	O
to	O
perform	O
some	O
or	O
all	O
DR	O
functions	O
.	O
</s>
