<s>
In	O
reliability	O
engineering	O
,	O
dual	B-Error_Name
modular	I-Error_Name
redundancy	I-Error_Name
(	O
DMR	O
)	O
is	O
when	O
components	O
of	O
a	O
system	O
are	O
duplicated	O
,	O
providing	O
redundancy	O
in	O
case	O
one	O
should	O
fail	O
.	O
</s>
<s>
It	O
is	O
particularly	O
applied	O
to	O
systems	O
where	O
the	O
duplicated	O
components	O
work	O
in	O
parallel	O
,	O
particularly	O
in	O
fault-tolerant	B-General_Concept
computer	I-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
DMR	O
provides	O
robustness	O
to	O
the	O
failure	O
of	O
one	O
component	O
,	O
and	O
error	B-Error_Name
detection	I-Error_Name
in	O
case	O
instruments	O
or	O
computers	O
that	O
should	O
give	O
the	O
same	O
result	O
give	O
different	O
results	O
,	O
but	O
does	O
not	O
provide	O
error	B-Error_Name
correction	I-Error_Name
,	O
as	O
which	O
component	O
is	O
correct	O
and	O
which	O
is	O
malfunctioning	O
cannot	O
be	O
automatically	O
determined	O
.	O
</s>
<s>
A	O
lockstep	B-General_Concept
fault-tolerant	B-General_Concept
machine	O
uses	O
replicated	O
elements	O
operating	O
in	O
parallel	O
.	O
</s>
<s>
A	O
machine	O
with	O
two	O
replications	O
of	O
each	O
element	O
is	O
termed	O
dual	B-Error_Name
modular	I-Error_Name
redundant	I-Error_Name
(	O
DMR	O
)	O
.	O
</s>
<s>
Examples	O
include	O
1ESS	B-Device
switch	I-Device
.	O
</s>
<s>
A	O
machine	O
with	O
three	O
replications	O
of	O
each	O
element	O
is	O
termed	O
triple	B-Error_Name
modular	I-Error_Name
redundant	I-Error_Name
(	O
TMR	O
)	O
.	O
</s>
