<s>
GEOM	B-Application
is	O
the	O
main	O
storage	O
framework	B-Architecture
for	O
the	O
FreeBSD	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
is	O
available	O
in	O
FreeBSD	B-Operating_System
5.0	O
and	O
later	O
releases	O
,	O
and	O
provides	O
a	O
standardized	O
way	O
to	O
access	O
storage	O
layers	O
.	O
</s>
<s>
GEOM	B-Application
is	O
modular	O
and	O
allows	O
for	O
geom	B-Application
modules	O
to	O
connect	O
to	O
the	O
framework	B-Architecture
.	O
</s>
<s>
A	O
number	O
of	O
modules	O
are	O
provided	O
as	O
part	O
of	O
FreeBSD	B-Operating_System
and	O
others	O
have	O
been	O
developed	O
independently	O
and	O
are	O
distributed	O
via	O
(	O
e.g.	O
)	O
</s>
<s>
GitHub	B-Application
.	O
</s>
<s>
GEOM	B-Application
was	O
developed	O
for	O
the	O
FreeBSD	B-Operating_System
Project	I-Operating_System
by	O
Poul-Henning	O
Kamp	O
and	O
NAI	O
Labs	O
,	O
the	O
Security	O
Research	O
Division	O
of	O
Network	O
Associates	O
,	O
Inc	O
.	O
under	O
DARPA/SPAWAR	O
contract	O
N66001-01-C-8035	O
(	O
"	O
CBOSS	O
"	O
)	O
,	O
as	O
part	O
of	O
the	O
DARPA	O
CHATS	O
research	O
program	O
.	O
</s>
<s>
Because	O
of	O
geom	B-Application
's	O
modular	O
design	O
,	O
modules	O
can	O
be	O
'	O
stacked	O
 '	O
together	O
to	O
form	O
a	O
chain	O
of	O
geom	B-Application
layers	O
.	O
</s>
<s>
A	O
provider	O
is	O
the	O
'	O
source	O
 '	O
of	O
the	O
geom	B-Application
module	O
,	O
often	O
a	O
physical	O
hard	B-Device
drive	I-Device
but	O
sometimes	O
a	O
virtualized	B-Application
disk	I-Application
such	O
as	O
a	O
memory	O
disk	O
.	O
</s>
<s>
The	O
geom	B-Application
module	O
in	O
turn	O
provides	O
an	O
'	O
output	O
 '	O
device	O
.	O
</s>
<s>
Other	O
geom	B-Application
modules	O
,	O
called	O
consumers	O
,	O
can	O
use	O
this	O
provider	O
to	O
create	O
a	O
chain	O
of	O
modules	O
connected	O
to	O
each	O
other	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
the	O
geom	B-Application
chain	O
,	O
often	O
a	O
filesystem	B-Application
is	O
applied	O
to	O
actually	O
use	O
the	O
geom	B-Application
provider	O
for	O
something	O
useful	O
.	O
</s>
<s>
The	O
provider	O
created	O
by	O
geom	B-Application
modules	O
behaves	O
just	O
like	O
a	O
physical	O
hard	B-Device
drive	I-Device
and	O
as	O
such	O
can	O
contain	O
filesystems	B-Application
such	O
as	O
FreeBSD	B-Operating_System
's	O
native	O
Unix	B-Operating_System
File	I-Operating_System
System	I-Operating_System
(	O
UFS	B-Operating_System
)	O
.	O
</s>
<s>
geom_eli	O
(	O
also	O
called	O
GELI	B-Application
,	O
provides	O
traditional	O
encryption	O
using	O
AES	B-Algorithm
,	O
Blowfish	B-Algorithm
,	O
Triple	B-Algorithm
DES	I-Algorithm
or	O
Camellia	B-Algorithm
algorithms	O
.	O
</s>
<s>
geom_flashmap	O
(	O
partition	B-Application
parts	O
of	O
e.g.	O
</s>
