<s>
The	O
SNIA	O
Common	O
RAID	B-Architecture
Disk	B-General_Concept
Data	I-General_Concept
Format	I-General_Concept
(	O
DDF	O
)	O
defines	O
a	O
standard	O
data	O
structure	O
describing	O
how	O
data	O
is	O
formatted	O
across	O
disks	O
in	O
a	O
RAID	B-Architecture
group	O
.	O
</s>
<s>
The	O
DDF	O
structure	O
allows	O
a	O
basic	O
level	O
of	O
interoperability	O
between	O
different	O
suppliers	O
of	O
RAID	B-Architecture
technology	O
.	O
</s>
<s>
The	O
Common	O
RAID	B-Architecture
DDF	O
structure	O
benefits	O
storage	O
users	O
by	O
enabling	O
in-place	O
data	O
migration	O
or	O
recovery	O
after	O
controller	O
failure	O
using	O
systems	O
from	O
different	O
vendors	O
.	O
</s>
<s>
DDF	O
is	O
an	O
external	O
metadata	O
format	O
that	O
is	O
compatible	O
with	O
the	O
mdraid	B-Application
subsystem	O
in	O
the	O
Linux	O
kernel	O
.	O
</s>
<s>
The	O
mdadm	B-Application
command-line	O
utility	O
is	O
a	O
part	O
of	O
the	O
mdraid	B-Application
subsystem	O
.	O
</s>
