<s>
Chipkill	B-Error_Name
is	O
IBM	O
's	O
trademark	O
for	O
a	O
form	O
of	O
advanced	O
error	B-Error_Name
checking	I-Error_Name
and	I-Error_Name
correcting	I-Error_Name
(	O
ECC	O
)	O
computer	B-General_Concept
memory	I-General_Concept
technology	O
that	O
protects	O
computer	B-General_Concept
memory	I-General_Concept
systems	O
from	O
any	O
single	O
memory	O
chip	O
failure	O
as	O
well	O
as	O
multi-bit	O
errors	O
from	O
any	O
portion	O
of	O
a	O
single	O
memory	O
chip	O
.	O
</s>
<s>
One	O
simple	O
scheme	O
to	O
perform	O
this	O
function	O
scatters	O
the	O
bits	O
of	O
a	O
Hamming	B-Error_Name
code	I-Error_Name
ECC	O
word	O
across	O
multiple	O
memory	O
chips	O
,	O
such	O
that	O
the	O
failure	O
of	O
any	O
single	O
memory	O
chip	O
will	O
affect	O
only	O
one	O
ECC	O
bit	O
per	O
word	O
.	O
</s>
<s>
Chipkill	B-Error_Name
is	O
frequently	O
combined	O
with	O
dynamic	O
bit-steering	O
,	O
so	O
that	O
if	O
a	O
chip	O
fails	O
(	O
or	O
has	O
exceeded	O
a	O
threshold	O
of	O
bit	O
errors	O
)	O
,	O
another	O
,	O
spare	O
,	O
memory	O
chip	O
is	O
used	O
to	O
replace	O
the	O
failed	O
chip	O
.	O
</s>
<s>
The	O
concept	O
is	O
similar	O
to	O
that	O
of	O
RAID	B-Architecture
,	O
which	O
protects	O
against	O
disk	O
failure	O
,	O
except	O
that	O
now	O
the	O
concept	O
is	O
applied	O
to	O
individual	O
memory	O
chips	O
.	O
</s>
<s>
An	O
important	O
RAS	B-General_Concept
feature	O
,	O
Chipkill	B-Error_Name
technology	O
is	O
deployed	O
primarily	O
on	O
SSDs	B-Device
,	O
mainframes	B-Architecture
and	O
midrange	O
servers	O
.	O
</s>
<s>
An	O
equivalent	O
system	O
from	O
Sun	O
Microsystems	O
is	O
called	O
Extended	B-Error_Name
ECC	I-Error_Name
,	O
while	O
equivalent	O
systems	O
from	O
HP	O
are	O
called	O
Advanced	B-Error_Name
ECC	I-Error_Name
and	O
Chipspare	B-Error_Name
.	O
</s>
<s>
A	O
similar	O
system	O
from	O
Intel	O
,	O
called	O
Lockstep	B-General_Concept
memory	O
,	O
provides	O
double-device	O
data	O
correction	O
(	O
DDDC	O
)	O
functionality	O
.	O
</s>
<s>
Similar	O
systems	O
from	O
Micron	O
,	O
called	O
redundant	O
array	O
of	O
independent	O
NAND	O
(	O
RAIN	O
)	O
,	O
and	O
from	O
SandForce	O
,	O
called	O
RAISE	O
level	O
2	O
,	O
protect	O
data	O
stored	O
on	O
SSDs	B-Device
from	O
any	O
single	O
NAND	O
flash	O
chip	O
going	O
bad	O
.	O
</s>
<s>
DIMMs	O
with	O
chipkill	B-Error_Name
error	B-Error_Name
correction	I-Error_Name
showed	O
a	O
lower	O
fraction	O
of	O
DIMMs	O
reporting	O
uncorrectable	O
errors	O
compared	O
to	O
DIMMs	O
with	O
error	O
correcting	O
codes	O
that	O
can	O
only	O
correct	O
single-bit	O
errors	O
.	O
</s>
<s>
A	O
2010	O
paper	O
from	O
University	O
of	O
Rochester	O
also	O
showed	O
that	O
Chipkill	B-Error_Name
memory	O
gave	O
substantially	O
lower	O
memory	O
errors	O
,	O
using	O
both	O
real	O
world	O
memory	O
traces	O
and	O
simulations	O
.	O
</s>
