<s>
GNU	O
ddrescue	B-Language
is	O
a	O
data	B-Application
recovery	I-Application
tool	O
for	O
disk	B-Device
drives	I-Device
,	O
DVDs	O
,	O
CDs	B-Device
,	O
and	O
other	O
digital	O
storage	O
media	O
.	O
</s>
<s>
It	O
copies	O
raw	O
blocks	O
of	O
storage	O
,	O
such	O
as	O
disk	B-Application
sectors	I-Application
,	O
from	O
one	O
device	O
or	O
file	O
to	O
another	O
,	O
while	O
handling	O
read	O
errors	O
in	O
an	O
intelligent	O
manner	O
to	O
minimize	O
data	O
loss	O
by	O
scraping	O
good	O
sectors	O
from	O
partially	O
read	O
blocks	O
.	O
</s>
<s>
GNU	O
ddrescue	B-Language
is	O
written	O
in	O
the	O
C++	B-Language
programming	I-Language
language	I-Language
,	O
and	O
is	O
available	O
as	O
open-source	B-License
software	O
that	O
was	O
originally	O
released	O
in	O
2004	O
.	O
</s>
<s>
It	O
is	O
also	O
available	O
in	O
binary	O
form	O
as	O
a	O
component	O
in	O
most	O
Linux	B-Application
distributions	I-Application
.	O
</s>
<s>
ddrescue	B-Language
uses	O
a	O
sophisticated	O
algorithm	O
to	O
copy	O
data	O
from	O
disk	B-Device
drives	I-Device
,	O
and	O
other	O
storage	O
devices	O
,	O
causing	O
as	O
little	O
additional	O
damage	O
,	O
if	O
they	O
are	O
failing	O
,	O
as	O
possible	O
.	O
</s>
<s>
It	O
is	O
considered	O
to	O
have	O
the	O
most	O
sophisticated	O
implementation	O
of	O
a	O
block-size-changing	O
algorithm	O
in	O
free	B-Application
and	I-Application
open	I-Application
source	I-Application
software	I-Application
,	O
and	O
is	O
considered	O
an	O
essential	O
data	B-Application
recovery	I-Application
tool	O
.	O
</s>
<s>
This	O
makes	O
it	O
possible	O
to	O
merge	O
multiple	O
defective	O
copies	O
of	O
CDs	B-Device
or	O
DVDs	O
into	O
one	O
backup	B-Protocol
file	O
.	O
</s>
<s>
ddrescue	B-Language
also	O
features	O
a	O
fill	O
mode	O
,	O
able	O
to	O
selectively	O
overwrite	O
parts	O
of	O
the	O
output	O
file	O
,	O
which	O
has	O
uses	O
such	O
as	O
wiping	O
data	O
,	O
marking	O
bad	O
areas	O
or	O
even	O
,	O
in	O
some	O
cases	O
,	O
repair	O
damaged	O
sectors	O
.	O
</s>
<s>
GNU	O
ddrescue	B-Language
is	O
not	O
a	O
derivative	O
of	O
dd	B-Application
which	O
also	O
copies	O
blocks	O
of	O
storage	O
from	O
disk	B-Device
storage	I-Device
,	O
but	O
does	O
not	O
operate	O
in	O
a	O
strategic	O
,	O
algorithmic	O
manner	O
.	O
</s>
<s>
GNU	O
ddrescue	B-Language
is	O
also	O
distinct	O
from	O
the	O
similarly	O
named	O
program	O
.	O
</s>
