<s>
Copyback	B-Device
is	O
a	O
NAND	O
flash	O
memory	O
or	O
SSD	B-Device
operation	O
where	O
data	O
is	O
read	O
from	O
one	O
location	O
in	O
flash	O
memory	O
and	O
written	O
to	O
another	O
location	O
,	O
usually	O
in	O
the	O
same	O
LUN	O
.	O
</s>
<s>
This	O
data	O
does	O
not	O
need	O
to	O
be	O
sent	O
to	O
the	O
host	O
as	O
the	O
copyback	B-Device
operation	O
does	O
not	O
originate	O
from	O
a	O
read	O
request	O
.	O
</s>
<s>
Copybacks	B-Device
are	O
closely	O
related	O
to	O
write	B-Error_Name
amplification	I-Error_Name
.	O
</s>
<s>
Copyback	B-Device
is	O
part	O
of	O
the	O
ONFI	B-General_Concept
specification	I-General_Concept
.	O
</s>
<s>
Copybacks	B-Device
are	O
done	O
for	O
a	O
variety	O
of	O
reasons	O
:	O
</s>
<s>
Wear	B-Application
Leveling	I-Application
:	O
Wear	B-Application
Leveling	I-Application
sometimes	O
requires	O
data	O
to	O
be	O
internally	O
moved	O
from	O
one	O
block	O
to	O
another	O
to	O
make	O
use	O
of	O
a	O
block	O
with	O
lower	O
program/erase	O
count	O
.	O
</s>
<s>
The	O
copyback	B-Device
operation	O
can	O
either	O
be	O
done	O
by	O
a	O
read	O
and	O
then	O
a	O
write	O
by	O
the	O
controller	O
or	O
as	O
an	O
NAND	O
flash	O
internal	O
copyback	B-Device
operation	O
.	O
</s>
<s>
However	O
,	O
the	O
internal	O
copyback	B-Device
operation	O
can	O
lead	O
to	O
errors	O
because	O
NAND	O
chips	O
do	O
not	O
have	O
error	O
detection	O
and	O
correction	O
inside	O
them	O
.	O
</s>
