<s>
Remote	B-Operating_System
File	I-Operating_System
Sharing	I-Operating_System
(	O
RFS	O
)	O
is	O
a	O
Unix	B-Application
operating	I-Application
system	I-Application
component	O
for	O
sharing	O
resources	O
,	O
such	O
as	O
files	O
,	O
devices	O
,	O
and	O
file	O
system	O
directories	O
,	O
across	O
a	O
network	O
,	O
in	O
a	O
network-independent	O
manner	O
,	O
similar	O
to	O
a	O
distributed	B-Protocol
file	I-Protocol
system	I-Protocol
.	O
</s>
<s>
It	O
was	O
developed	O
at	O
Bell	O
Laboratories	O
of	O
AT&T	O
in	O
the	O
1980s	O
,	O
and	O
was	O
first	O
delivered	O
with	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
Release	O
3	O
(	O
SVR3	B-Operating_System
)	O
.	O
</s>
<s>
It	O
was	O
also	O
included	O
in	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
Release	O
4	O
,	O
but	O
as	O
that	O
also	O
included	O
the	O
Network	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
NFS	O
)	O
which	O
was	O
based	O
on	O
TCP/IP	B-Protocol
and	O
more	O
widely	O
supported	O
in	O
the	O
computing	O
industry	O
,	O
RFS	O
was	O
little	O
used	O
.	O
</s>
<s>
Some	O
licensees	O
of	O
AT&T	B-Operating_System
UNIX	I-Operating_System
System	B-Operating_System
V	I-Operating_System
Release	O
4	O
did	O
not	O
include	O
RFS	O
support	O
in	O
SVR4	O
distributions	O
,	O
and	O
Sun	O
Microsystems	O
removed	O
it	O
from	O
Solaris	B-Application
2.4	O
.	O
</s>
<s>
The	O
basic	O
application	O
architecture	O
of	O
RFS	O
is	O
the	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
model	I-Operating_System
,	O
in	O
which	O
a	O
participating	O
host	O
may	O
be	O
a	O
server	B-Application
as	O
well	O
as	O
a	O
client	O
,	O
simultaneously	O
.	O
</s>
<s>
It	O
was	O
based	O
on	O
different	O
design	O
decisions	O
,	O
in	O
comparison	O
to	O
the	O
Network	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
NFS	O
)	O
.	O
</s>
<s>
Instead	O
of	O
focusing	O
on	O
reliable	O
operation	O
in	O
the	O
presence	O
of	O
failures	O
,	O
it	O
focused	O
on	O
preserving	O
UNIX	B-Application
file	O
system	O
semantics	O
across	O
the	O
network	O
.	O
</s>
<s>
This	O
enabled	O
the	O
system	O
to	O
provide	O
remote	O
access	O
to	O
hardware	O
resources	O
located	O
on	O
an	O
RFS	O
server	B-Application
.	O
</s>
<s>
Unlike	O
NFS	O
(	O
before	O
version	O
4	O
)	O
,	O
the	O
RFS	O
server	B-Application
maintains	O
state	O
to	O
keep	O
track	O
of	O
how	O
many	O
times	O
a	O
file	O
has	O
been	O
opened	O
,	O
or	O
the	O
locks	B-Operating_System
established	O
on	O
a	O
file	O
or	O
device	O
.	O
</s>
<s>
RFS	O
provides	O
complete	O
UNIX/POSIX	O
file	O
semantics	O
for	O
all	O
file	O
types	O
,	O
including	O
special	O
devices	O
,	O
and	O
named	O
pipes	O
.	O
</s>
<s>
It	O
supports	O
access	O
controls	O
and	O
record	O
and	O
file	B-Application
locking	I-Application
of	O
remote	O
files	O
in	O
a	O
transparent	O
manner	O
as	O
if	O
the	O
shared	O
files	O
are	O
local	O
.	O
</s>
<s>
For	O
this	O
it	O
relies	O
on	O
the	O
System	B-Operating_System
V	I-Operating_System
STREAMS	O
mechanism	O
using	O
the	O
Transport	O
Provider	O
Interface	O
.	O
</s>
