<s>
Distributed	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
DFS	B-Protocol
)	O
is	O
a	O
set	O
of	O
client	O
and	O
server	O
services	O
that	O
allow	O
an	O
organization	O
using	O
Microsoft	B-Application
Windows	I-Application
servers	O
to	O
organize	O
many	O
distributed	O
SMB	B-Operating_System
file	O
shares	O
into	O
a	O
distributed	B-Protocol
file	I-Protocol
system	I-Protocol
.	O
</s>
<s>
DFS	B-Protocol
has	O
two	O
components	O
to	O
its	O
service	O
:	O
Location	O
transparency	O
(	O
via	O
the	O
namespace	O
component	O
)	O
and	O
Redundancy	O
(	O
via	O
the	O
file	O
replication	O
component	O
)	O
.	O
</s>
<s>
Together	O
,	O
these	O
components	O
enable	O
data	O
availability	O
in	O
the	O
case	O
of	O
failure	O
or	O
heavy	O
load	O
by	O
allowing	O
shares	O
in	O
multiple	O
different	O
locations	O
to	O
be	O
logically	O
grouped	O
under	O
one	O
folder	O
,	O
the	O
"	O
DFS	B-Protocol
root	O
"	O
.	O
</s>
<s>
Microsoft	O
's	O
DFS	B-Protocol
is	O
referred	O
to	O
interchangeably	O
as	O
'	O
DFS	B-Protocol
 '	O
and	O
'	O
Dfs	B-Protocol
 '	O
by	O
Microsoft	O
and	O
is	O
unrelated	O
to	O
the	O
DCE	B-Protocol
Distributed	I-Protocol
File	I-Protocol
System	I-Protocol
,	O
which	O
held	O
the	O
'	O
DFS	B-Protocol
 '	O
trademark	O
but	O
was	O
discontinued	O
in	O
2005	O
.	O
</s>
<s>
It	O
is	O
also	O
called	O
"	O
MS-DFS	O
"	O
or	O
"	O
MSDFS	O
"	O
in	O
some	O
contexts	O
,	O
e.g.	O
</s>
<s>
in	O
the	O
Samba	B-Language
user	B-Operating_System
space	I-Operating_System
project	O
.	O
</s>
<s>
There	O
is	O
no	O
requirement	O
to	O
use	O
the	O
two	O
components	O
of	O
DFS	B-Protocol
together	O
;	O
it	O
is	O
perfectly	O
possible	O
to	O
use	O
the	O
logical	O
namespace	O
component	O
without	O
using	O
DFS	B-Protocol
file	O
replication	O
,	O
and	O
it	O
is	O
perfectly	O
possible	O
to	O
use	O
file	O
replication	O
between	O
servers	O
without	O
combining	O
them	O
into	O
one	O
namespace	O
.	O
</s>
<s>
A	O
DFS	B-Protocol
root	O
can	O
only	O
exist	O
on	O
a	O
server	O
version	O
of	O
Windows	O
(	O
from	O
Windows	B-Device
NT	I-Device
4.0	I-Device
and	O
up	O
)	O
and	O
OpenSolaris	B-Operating_System
(	O
in	O
kernel	B-Operating_System
space	I-Operating_System
)	O
or	O
a	O
computer	O
running	O
Samba	B-Language
(	O
in	O
user	B-Operating_System
space	I-Operating_System
.	O
)	O
</s>
<s>
The	O
Enterprise	O
and	O
Datacenter	O
Editions	O
of	O
Windows	O
Server	O
can	O
host	O
multiple	O
DFS	B-Protocol
roots	O
on	O
the	O
same	O
server	O
.	O
</s>
<s>
OpenSolaris	B-Operating_System
intends	O
on	O
supporting	O
multiple	O
DFS	B-Protocol
roots	O
in	O
"	O
a	O
future	O
project	O
based	O
on	O
Active	B-Protocol
Directory	I-Protocol
(	O
AD	O
)	O
domain-based	O
DFS	B-Protocol
namespaces	O
"	O
.	O
</s>
<s>
There	O
are	O
two	O
ways	O
of	O
implementing	O
DFS	B-Protocol
on	O
a	O
server	O
:	O
</s>
<s>
Standalone	O
DFS	B-Protocol
namespace	O
-	O
allows	O
for	O
a	O
DFS	B-Protocol
root	O
that	O
exists	O
only	O
on	O
the	O
local	O
computer	O
,	O
and	O
thus	O
does	O
not	O
use	O
Active	B-Protocol
Directory	I-Protocol
.	O
</s>
<s>
A	O
Standalone	O
DFS	B-Protocol
can	O
only	O
be	O
accessed	O
on	O
the	O
computer	O
on	O
which	O
it	O
is	O
created	O
.	O
</s>
<s>
It	O
does	O
not	O
offer	O
any	O
fault	B-General_Concept
tolerance	I-General_Concept
and	O
cannot	O
be	O
linked	O
to	O
any	O
other	O
DFS	B-Protocol
.	O
</s>
<s>
This	O
is	O
the	O
only	O
option	O
available	O
on	O
Windows	B-Device
NT	I-Device
4.0	I-Device
Server	O
systems	O
.	O
</s>
<s>
Standalone	O
DFS	B-Protocol
roots	O
are	O
rarely	O
encountered	O
because	O
of	O
their	O
limited	O
utility	O
.	O
</s>
<s>
Domain-based	O
DFS	B-Protocol
namespace	O
-	O
stores	O
the	O
DFS	B-Protocol
configuration	O
in	O
Active	B-Protocol
Directory	I-Protocol
,	O
making	O
the	O
DFS	B-Protocol
namespace	O
root	O
accessible	O
at	O
or	O
The	O
namespace	O
roots	O
can	O
reside	O
on	O
a	O
domain	B-Protocol
controller	I-Protocol
or	O
a	O
domain	O
member	O
server	O
.	O
</s>
<s>
If	O
domain	B-Protocol
controllers	I-Protocol
are	O
not	O
used	O
as	O
the	O
namespace	O
root	O
servers	O
,	O
multiple	O
member	O
servers	O
should	O
be	O
used	O
to	O
provide	O
full	O
fault	B-General_Concept
tolerance	I-General_Concept
.	O
</s>
<s>
Traditional	O
file	O
shares	O
,	O
associated	O
with	O
a	O
single	O
server	O
,	O
have	O
SMB	B-Operating_System
paths	O
of	O
the	O
form	O
Domain-based	O
DFS	B-Protocol
file	O
share	O
paths	O
are	O
distinguished	O
by	O
using	O
the	O
domain	O
name	O
in	O
place	O
of	O
the	O
server	O
name	O
,	O
in	O
the	O
form	O
When	O
a	O
user	O
accesses	O
such	O
a	O
share	O
,	O
either	O
directly	O
or	O
by	O
mapping	B-General_Concept
a	I-General_Concept
drive	I-General_Concept
,	O
their	O
computer	O
will	O
access	O
one	O
of	O
the	O
available	O
servers	O
associated	O
with	O
that	O
share	O
,	O
following	O
rules	O
which	O
can	O
be	O
configured	O
by	O
the	O
network	O
administrator	O
.	O
</s>
<s>
One	O
major	O
caveat	O
regarding	O
this	O
flexibility	O
is	O
that	O
currently-open	O
files	O
will	O
potentially	O
become	O
unusable	O
,	O
as	O
open	O
files	O
cannot	O
be	O
failed-over	B-General_Concept
.	O
</s>
<s>
Early	O
versions	O
of	O
DFS	B-Protocol
used	O
Microsoft	O
's	O
File	B-Protocol
Replication	I-Protocol
Service	I-Protocol
(	O
FRS	O
)	O
which	O
provides	O
basic	O
file	O
replication	O
capability	O
between	O
servers	O
.	O
</s>
<s>
Windows	O
Server	O
2003	O
R2	O
introduced	O
"	O
DFS	B-Protocol
Replication	I-Protocol
"	O
(	O
DFSR	O
)	O
which	O
improves	O
on	O
FRS	O
by	O
only	O
copying	O
those	O
parts	O
of	O
files	O
which	O
have	O
changed	O
(	O
remote	O
differential	O
compression	O
)	O
,	O
by	O
using	O
data	O
compression	O
to	O
reduce	O
network	O
traffic	O
,	O
and	O
by	O
allowing	O
administrators	O
flexible	O
configuration	O
options	O
for	O
limiting	O
network	O
traffic	O
with	O
a	O
customizable	O
schedule	O
.	O
</s>
<s>
The	O
server	O
component	O
of	O
Distributed	B-Protocol
File	I-Protocol
System	I-Protocol
was	O
first	O
introduced	O
as	O
an	O
add-on	O
to	O
Windows	B-Device
NT	I-Device
4.0	I-Device
Server	O
,	O
called	O
"	O
DFS	B-Protocol
4.1	O
"	O
,	O
and	O
was	O
later	O
included	O
as	O
a	O
standard	O
component	O
of	O
all	O
editions	O
of	O
Windows	B-Application
2000	I-Application
Server	O
.	O
</s>
<s>
Client-side	O
support	O
is	O
included	O
in	O
Windows	B-Device
NT	I-Device
4.0	I-Device
and	O
later	O
versions	O
of	O
Windows	O
.	O
</s>
<s>
Linux	O
kernels	O
2.6.14	O
and	O
later	O
come	O
with	O
an	O
SMB	B-Operating_System
client	O
VFS	B-Application
called	O
"	O
cifs	B-Operating_System
"	O
that	O
supports	O
DFS	B-Protocol
.	O
</s>
<s>
On	O
Mac	O
OS	O
X	O
DFS	B-Protocol
is	O
supported	O
natively	O
in	O
Mac	B-Application
OS	I-Application
X	I-Application
10.7	I-Application
(	O
"	O
Lion	B-Application
"	O
)	O
onward	O
.	O
</s>
<s>
There	O
are	O
a	O
number	O
of	O
specifications	O
that	O
are	O
relevant	O
to	O
DFS	B-Protocol
,	O
they	O
are	O
available	O
through	O
the	O
Microsoft	O
Open	O
Specifications	O
program	O
:	O
</s>
<s>
Specifies	O
the	O
Distributed	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
DFS	B-Protocol
)	O
:	O
Referral	O
Protocol	O
,	O
which	O
enables	O
file	O
system	O
clients	O
to	O
resolve	O
names	O
from	O
a	O
namespace	O
distributed	O
across	O
many	O
servers	O
and	O
geographies	O
into	O
local	O
names	O
on	O
specific	O
file	O
servers	O
.	O
</s>
<s>
Specifies	O
the	O
Distributed	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
DFS	B-Protocol
)	O
:	O
Namespace	O
Management	O
Protocol	O
,	O
which	O
provides	O
an	O
RPC	O
interface	O
for	O
administering	O
DFS	B-Protocol
configurations	O
.	O
</s>
<s>
The	O
client	O
is	O
an	O
application	O
that	O
issues	O
method	O
calls	O
on	O
the	O
RPC	O
interface	O
to	O
administer	O
DFS	B-Protocol
.	O
</s>
<s>
The	O
server	O
is	O
a	O
DFS	B-Protocol
service	O
that	O
implements	O
support	O
for	O
this	O
RPC	O
interface	O
for	O
administering	O
DFS	B-Protocol
.	O
</s>
<s>
Specifies	O
the	O
DFS	B-Protocol
Replication	I-Protocol
Helper	O
Protocol	O
,	O
which	O
is	O
made	O
up	O
of	O
a	O
set	O
of	O
distributed	O
component	O
object	O
model	O
(	O
DCOM	O
)	O
interfaces	O
for	O
configuring	O
and	O
monitoring	O
DFS	B-Protocol
Replication	I-Protocol
Helper	O
Protocols	O
on	O
a	O
server	O
.	O
</s>
