<s>
Network	B-Protocol
File	I-Protocol
System	I-Protocol
(	O
NFS	O
)	O
is	O
a	O
distributed	B-Protocol
file	I-Protocol
system	I-Protocol
protocol	O
originally	O
developed	O
by	O
Sun	O
Microsystems	O
(	O
Sun	O
)	O
in	O
1984	O
,	O
allowing	O
a	O
user	O
on	O
a	O
client	B-Protocol
computer	I-Protocol
to	O
access	O
files	O
over	O
a	O
computer	B-Architecture
network	I-Architecture
much	O
like	O
local	O
storage	O
is	O
accessed	O
.	O
</s>
<s>
NFS	O
,	O
like	O
many	O
other	O
protocols	O
,	O
builds	O
on	O
the	O
Open	B-Protocol
Network	I-Protocol
Computing	I-Protocol
Remote	I-Protocol
Procedure	I-Protocol
Call	I-Protocol
(	O
ONC	B-Protocol
RPC	I-Protocol
)	O
system	O
.	O
</s>
<s>
Version2	O
of	O
the	O
protocol	O
(	O
defined	O
in	O
RFC	O
1094	O
,	O
March	O
1989	O
)	O
originally	O
operated	O
only	O
over	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	O
)	O
.	O
</s>
<s>
Its	O
designers	O
meant	O
to	O
keep	O
the	O
server	B-Application
side	O
stateless	B-Protocol
,	O
with	O
locking	B-Operating_System
(	O
for	O
example	O
)	O
implemented	O
outside	O
of	O
the	O
core	O
protocol	O
.	O
</s>
<s>
The	O
Virtual	B-Application
File	I-Application
System	I-Application
interface	O
allows	O
a	O
modular	O
implementation	O
,	O
reflected	O
in	O
a	O
simple	O
protocol	O
.	O
</s>
<s>
By	O
February	O
1986	O
,	O
implementations	O
were	O
demonstrated	O
for	O
operating	O
systems	O
such	O
as	O
System	B-Operating_System
V	I-Operating_System
release2	O
,	O
DOS	B-Device
,	O
and	O
VAX/VMS	B-Operating_System
using	O
Eunice	B-Operating_System
.	O
</s>
<s>
support	O
for	O
asynchronous	O
writes	O
on	O
the	O
server	B-Application
,	O
to	O
improve	O
write	O
performance	O
;	O
</s>
<s>
a	O
READDIRPLUS	O
operation	O
,	O
to	O
get	O
file	O
handles	O
and	O
attributes	O
along	O
with	O
file	O
names	O
when	O
scanning	O
a	O
directory	B-Application
;	O
</s>
<s>
This	O
became	O
an	O
acute	O
pain	O
point	O
for	O
Digital	O
Equipment	O
Corporation	O
with	O
the	O
introduction	O
of	O
a	O
64-bit	O
version	O
of	O
Ultrix	B-Operating_System
to	O
support	O
their	O
newly	O
released	O
64-bit	O
RISC	B-Architecture
processor	I-Architecture
,	O
the	O
Alpha	B-General_Concept
21064	I-General_Concept
.	O
</s>
<s>
At	O
the	O
time	O
of	O
introduction	O
of	O
Version3	O
,	O
vendor	O
support	O
for	O
TCP	B-Protocol
as	O
a	O
transport-layer	B-Architecture
protocol	I-Architecture
began	O
increasing	O
.	O
</s>
<s>
While	O
several	O
vendors	O
had	O
already	O
added	O
support	O
for	O
NFS	O
Version2	O
with	O
TCP	B-Protocol
as	O
a	O
transport	O
,	O
Sun	O
Microsystems	O
added	O
support	O
for	O
TCP	B-Protocol
as	O
a	O
transport	O
for	O
NFS	O
at	O
the	O
same	O
time	O
it	O
added	O
support	O
for	O
Version3	O
.	O
</s>
<s>
Using	O
TCP	B-Protocol
as	O
a	O
transport	O
made	O
using	O
NFS	O
over	O
a	O
WAN	O
more	O
feasible	O
,	O
and	O
allowed	O
the	O
use	O
of	O
larger	O
read	O
and	O
write	O
transfer	O
sizes	O
beyond	O
the	O
8KB	O
limit	O
imposed	O
by	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
.	O
</s>
<s>
WebNFS	B-Protocol
was	O
an	O
extension	O
to	O
NFSv2	O
and	O
NFSv3	B-Protocol
allowing	O
it	O
to	O
function	O
behind	O
restrictive	O
firewalls	B-Application
without	O
the	O
complexity	O
of	O
Portmap	O
and	O
MOUNT	O
protocols	O
.	O
</s>
<s>
WebNFS	B-Protocol
had	O
a	O
fixed	O
TCP/UDP	B-Protocol
port	I-Protocol
number	I-Protocol
(	O
2049	O
)	O
,	O
and	O
instead	O
of	O
requiring	O
the	O
client	B-Protocol
to	O
contact	O
the	O
MOUNT	O
RPC	O
service	O
to	O
determine	O
the	O
initial	O
filehandle	O
of	O
every	O
filesystem	B-Application
,	O
it	O
introduced	O
the	O
concept	O
of	O
a	O
public	O
filehandle	O
(	O
null	O
for	O
NFSv2	O
,	O
zero-length	O
for	O
NFSv3	B-Protocol
)	O
which	O
could	O
be	O
used	O
as	O
the	O
starting	O
point	O
.	O
</s>
<s>
Version4	O
(	O
RFC	O
3010	O
,	O
December	O
2000	O
;	O
revised	O
in	O
RFC	O
3530	O
,	O
April	O
2003	O
and	O
again	O
in	O
RFC	O
7530	O
,	O
March	O
2015	O
)	O
,	O
influenced	O
by	O
Andrew	B-Application
File	I-Application
System	I-Application
(	O
AFS	O
)	O
and	O
Server	B-Operating_System
Message	I-Operating_System
Block	I-Operating_System
(	O
SMB	O
,	O
also	O
termed	O
CIFS	B-Operating_System
)	O
,	O
includes	O
performance	O
improvements	O
,	O
mandates	O
strong	O
security	O
,	O
and	O
introduces	O
a	O
stateful	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
Version	O
4	O
became	O
the	O
first	O
version	O
developed	O
with	O
the	O
Internet	O
Engineering	O
Task	O
Force	O
(	O
IETF	O
)	O
after	O
Sun	O
Microsystems	O
handed	O
over	O
the	O
development	O
of	O
the	O
NFS	B-Protocol
protocols	I-Protocol
.	O
</s>
<s>
NFS	O
version4.1	O
(	O
RFC	O
5661	O
,	O
January	O
2010	O
;	O
revised	O
in	O
RFC	O
8881	O
,	O
August	O
2020	O
)	O
aims	O
to	O
provide	O
protocol	O
support	O
to	O
take	O
advantage	O
of	O
clustered	O
server	B-Application
deployments	O
including	O
the	O
ability	O
to	O
provide	O
scalable	O
parallel	O
access	O
to	O
files	O
distributed	O
among	O
multiple	O
servers	O
(	O
pNFS	O
extension	O
)	O
.	O
</s>
<s>
Version4.1	O
includes	O
Session	O
trunking	O
mechanism	O
(	O
Also	O
known	O
as	O
NFS	O
Multipathing	O
)	O
and	O
available	O
in	O
some	O
enterprise	O
solutions	O
as	O
VMware	B-Operating_System
ESXi	I-Operating_System
.	O
</s>
<s>
NFS	O
version4.2	O
(	O
RFC	O
7862	O
)	O
was	O
published	O
in	O
November	O
2016	O
with	O
new	O
features	O
including	O
:	O
server-side	O
clone	O
and	O
copy	O
,	O
application	O
I/O	O
advise	O
,	O
sparse	O
files	O
,	O
space	O
reservation	O
,	O
application	O
data	O
block	O
(	O
ADB	O
)	O
,	O
labeled	O
NFS	O
with	O
sec_label	O
that	O
accommodates	O
any	O
MAC	O
security	O
system	O
,	O
and	O
two	O
new	O
operations	O
for	O
pNFS	O
(	O
LAYOUTERROR	O
and	O
LAYOUTSTATS	O
)	O
.	O
</s>
<s>
One	O
big	O
advantage	O
of	O
NFSv4	O
over	O
its	O
predecessors	O
is	O
that	O
only	O
one	O
UDP	O
or	O
TCP	B-Protocol
port	O
,	O
2049	O
,	O
is	O
used	O
to	O
run	O
the	O
service	O
,	O
which	O
simplifies	O
using	O
the	O
protocol	O
across	O
firewalls	B-Application
.	O
</s>
<s>
WebNFS	B-Protocol
,	O
an	O
extension	O
to	O
Version2	O
and	O
Version3	O
,	O
allows	O
NFS	O
to	O
integrate	O
more	O
easily	O
into	O
Web-browsers	O
and	O
to	O
enable	O
operation	O
through	O
firewalls	B-Application
.	O
</s>
<s>
In	O
2007	O
Sun	O
Microsystems	O
open-sourced	O
their	O
client-side	O
WebNFS	B-Protocol
implementation	O
.	O
</s>
<s>
NFS-Ganesha	O
,	O
an	O
NFS	O
server	B-Application
,	O
running	O
in	O
user-space	O
and	O
supporting	O
various	O
file	B-Application
systems	I-Application
like	O
GPFS/Spectrum	B-Application
Scale	I-Application
,	O
CephFS	B-Operating_System
via	O
respective	O
FSAL	O
(	O
File	B-Application
System	I-Application
Abstraction	O
Layer	O
)	O
modules	O
.	O
</s>
<s>
NFS	O
is	O
often	O
used	O
with	O
Unix	B-Application
operating	I-Application
systems	I-Application
(	O
such	O
as	O
Solaris	B-Application
,	O
AIX	B-Application
,	O
HP-UX	B-Application
)	O
,	O
Apple	O
's	O
macOS	B-Application
,	O
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
such	O
as	O
Linux	B-Application
and	O
FreeBSD	B-Operating_System
)	O
.	O
</s>
<s>
It	O
is	O
also	O
available	O
to	O
operating	O
systems	O
such	O
as	O
Acorn	B-Operating_System
RISC	I-Operating_System
OS	I-Operating_System
,	O
AmigaOS	B-Application
,	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
,	O
OpenVMS	B-Operating_System
,	O
MS-DOS	B-Application
,	O
Microsoft	B-Application
Windows	I-Application
,	O
OS/2	B-Application
,	O
ArcaOS	B-Device
,	O
Novell	B-Operating_System
NetWare	I-Operating_System
,	O
and	O
IBM	B-Application
i	I-Application
.	O
</s>
<s>
Alternative	O
remote	O
file	B-Application
access	I-Application
protocols	O
include	O
the	O
Server	B-Operating_System
Message	I-Operating_System
Block	I-Operating_System
(	O
SMB	O
,	O
also	O
termed	O
CIFS	B-Operating_System
)	O
,	O
Apple	B-Protocol
Filing	I-Protocol
Protocol	I-Protocol
(	O
AFP	O
)	O
,	O
NetWare	B-Protocol
Core	I-Protocol
Protocol	I-Protocol
(	O
NCP	O
)	O
,	O
and	O
OS/400	B-Application
File	O
Server	B-Application
file	B-Application
system	I-Application
(	O
QFileSvr.400	O
)	O
.	O
</s>
<s>
SMB	O
and	O
NetWare	B-Protocol
Core	I-Protocol
Protocol	I-Protocol
(	O
NCP	O
)	O
occur	O
more	O
often	O
than	O
NFS	O
on	O
systems	O
running	O
Microsoft	B-Application
Windows	I-Application
;	O
AFP	O
occurs	O
more	O
often	O
than	O
NFS	O
in	O
Apple	O
Macintosh	B-Application
systems	I-Application
;	O
and	O
QFileSvr.400	O
occurs	O
more	O
often	O
in	O
IBM	B-Application
i	I-Application
systems	O
.	O
</s>
<s>
Haiku	B-Language
in	O
2012	O
added	O
NFSv4	O
support	O
as	O
part	O
of	O
a	O
Google	O
Summer	O
of	O
Code	O
project	O
.	O
</s>
<s>
Assuming	O
a	O
Unix-style	B-Operating_System
scenario	O
in	O
which	O
one	O
machine	O
(	O
the	O
client	B-Protocol
)	O
needs	O
access	O
to	O
data	O
stored	O
on	O
another	O
machine	O
(	O
the	O
NFS	O
server	B-Application
)	O
:	O
</s>
<s>
The	O
server	B-Application
implements	O
NFS	O
daemon	B-Operating_System
processes	O
,	O
running	O
by	O
default	O
as	O
nfsd	B-Protocol
,	O
to	O
make	O
its	O
data	O
generically	O
available	O
to	O
clients	O
.	O
</s>
<s>
The	O
server	B-Application
administrator	O
determines	O
what	O
to	O
make	O
available	O
,	O
exporting	O
the	O
names	O
and	O
parameters	O
of	O
directories	B-Application
,	O
typically	O
using	O
the	O
/etc/exports	O
configuration	O
file	O
and	O
the	O
exportfs	O
command	O
.	O
</s>
<s>
The	O
server	B-Application
security-administration	O
ensures	O
that	O
it	O
can	O
recognize	O
and	O
approve	O
validated	O
clients	O
.	O
</s>
<s>
The	O
server	B-Application
network	O
configuration	O
ensures	O
that	O
appropriate	O
clients	O
can	O
negotiate	O
with	O
it	O
through	O
any	O
firewall	B-Application
system	O
.	O
</s>
<s>
The	O
client	B-Protocol
machine	I-Protocol
requests	O
access	O
to	O
exported	O
data	O
,	O
typically	O
by	O
issuing	O
a	O
mount	O
command	O
.	O
</s>
<s>
If	O
all	O
goes	O
well	O
,	O
users	O
on	O
the	O
client	B-Protocol
machine	I-Protocol
can	O
then	O
view	O
and	O
interact	O
with	O
mounted	O
filesystems	B-Application
on	O
the	O
server	B-Application
within	O
the	O
parameters	O
permitted	O
.	O
</s>
<s>
Note	O
that	O
automation	O
of	O
the	O
NFS	O
mounting	O
process	O
may	O
take	O
place	O
—	O
perhaps	O
using	O
/etc/fstab	O
and/or	O
automounting	B-Protocol
facilities	O
.	O
</s>
<s>
During	O
the	O
development	O
of	O
the	O
ONC	O
protocol	O
(	O
called	O
SunRPC	B-Protocol
at	O
the	O
time	O
)	O
,	O
only	O
Apollo	O
's	O
Network	B-Protocol
Computing	I-Protocol
System	I-Protocol
(	O
NCS	O
)	O
offered	O
comparable	O
functionality	O
.	O
</s>
<s>
Arguments	O
focused	O
on	O
the	O
method	O
for	O
data-encoding	O
—	O
ONC	O
's	O
External	B-Protocol
Data	I-Protocol
Representation	I-Protocol
(	O
XDR	O
)	O
always	O
rendered	O
integers	O
in	O
big-endian	O
order	O
,	O
even	O
if	O
both	O
peers	O
of	O
the	O
connection	O
had	O
little-endian	O
machine-architectures	O
,	O
whereas	O
NCS	O
's	O
method	O
attempted	O
to	O
avoid	O
byte-swap	O
whenever	O
two	O
peers	O
shared	O
a	O
common	O
endianness	O
in	O
their	O
machine-architectures	O
.	O
</s>
<s>
In	O
1987	O
,	O
Sun	O
and	O
AT&T	O
announced	O
they	O
would	O
jointly	O
develop	O
T	O
's	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
Release	O
4	O
.	O
</s>
<s>
This	O
caused	O
many	O
of	O
T	O
's	O
other	O
licensees	O
of	O
UNIX	B-Application
System	I-Application
to	O
become	O
concerned	O
that	O
this	O
would	O
put	O
Sun	O
in	O
an	O
advantaged	O
position	O
,	O
and	O
ultimately	O
led	O
to	O
Digital	O
Equipment	O
,	O
HP	O
,	O
IBM	O
,	O
and	O
others	O
forming	O
the	O
Open	B-Application
Software	I-Application
Foundation	I-Application
(	O
OSF	O
)	O
in	O
1988	O
.	O
</s>
<s>
Ironically	O
,	O
Sun	O
and	O
AT&T	O
had	O
formerly	O
competed	O
over	O
Sun	O
's	O
NFS	O
versus	O
T	O
's	O
Remote	B-Operating_System
File	I-Operating_System
System	I-Operating_System
(	O
RFS	O
)	O
,	O
and	O
the	O
quick	O
adoption	O
of	O
NFS	O
over	O
RFS	O
by	O
Digital	O
Equipment	O
,	O
HP	O
,	O
IBM	O
,	O
and	O
many	O
other	O
computer	O
vendors	O
tipped	O
the	O
majority	O
of	O
users	O
in	O
favor	O
of	O
NFS	O
.	O
</s>
<s>
OSF	O
adopted	O
the	O
Distributed	B-Operating_System
Computing	I-Operating_System
Environment	I-Operating_System
(	O
DCE	O
)	O
and	O
the	O
DCE	B-Protocol
Distributed	I-Protocol
File	I-Protocol
System	I-Protocol
(	O
DFS	B-Protocol
)	O
over	O
Sun/ONC	O
RPC	O
and	O
NFS	O
.	O
</s>
<s>
DFS	B-Protocol
used	O
DCE	O
as	O
the	O
RPC	O
,	O
and	O
DFS	B-Protocol
derived	O
from	O
the	O
Andrew	B-Application
File	I-Application
System	I-Application
(	O
AFS	O
)	O
;	O
DCE	O
itself	O
derived	O
from	O
a	O
suite	O
of	O
technologies	O
,	O
including	O
Apollo	O
's	O
NCS	O
and	O
Kerberos	B-Protocol
.	O
</s>
<s>
Sun	O
Microsystems	O
and	O
the	O
Internet	O
Society	O
(	O
ISOC	O
)	O
reached	O
an	O
agreement	O
to	O
cede	O
"	O
change	O
control	O
"	O
of	O
ONC	B-Protocol
RPC	I-Protocol
so	O
that	O
the	O
ISOC	O
's	O
engineering-standards	O
body	O
,	O
the	O
Internet	O
Engineering	O
Task	O
Force	O
(	O
IETF	O
)	O
,	O
could	O
publish	O
standards	O
documents	O
(	O
RFCs	O
)	O
related	O
to	O
ONC	B-Protocol
RPC	I-Protocol
protocols	O
and	O
could	O
extend	O
ONC	B-Protocol
RPC	I-Protocol
.	O
</s>
<s>
Later	O
,	O
the	O
IETF	O
chose	O
to	O
extend	O
ONC	B-Protocol
RPC	I-Protocol
by	O
adding	O
a	O
new	O
authentication	O
flavor	O
based	O
on	O
Generic	O
Security	O
Services	O
Application	O
Program	O
Interface	O
(	O
GSSAPI	O
)	O
,	O
RPCSEC	O
GSS	O
,	O
to	O
meet	O
IETF	O
requirements	O
that	O
protocol	O
standards	O
have	O
adequate	O
security	O
.	O
</s>
<s>
Instead	O
,	O
ISOC	O
gained	O
the	O
right	O
to	O
add	O
new	O
versions	O
to	O
the	O
NFS	B-Protocol
protocol	I-Protocol
,	O
which	O
resulted	O
in	O
IETF	O
specifying	O
NFS	O
version	O
4	O
in	O
2003	O
.	O
</s>
<s>
By	O
the	O
21st	O
century	O
,	O
neither	O
DFS	B-Protocol
nor	O
AFS	O
had	O
achieved	O
any	O
major	O
commercial	O
success	O
as	O
compared	O
to	O
SMB-CIFS	O
or	O
NFS	O
.	O
</s>
<s>
IBM	O
,	O
which	O
had	O
formerly	O
acquired	O
the	O
primary	O
commercial	O
vendor	O
of	O
DFS	B-Protocol
and	O
AFS	O
,	O
Transarc	O
,	O
donated	O
most	O
of	O
the	O
AFS	O
source	O
code	O
to	O
the	O
free	O
software	O
community	O
in	O
2000	O
.	O
</s>
<s>
The	O
OpenAFS	B-Application
project	O
lives	O
on	O
.	O
</s>
<s>
In	O
early	O
2005	O
,	O
IBM	O
announced	O
end	O
of	O
sales	O
for	O
AFS	O
and	O
DFS	B-Protocol
.	O
</s>
<s>
The	O
NFSv4.1	O
protocol	O
defines	O
a	O
method	O
of	O
separating	O
the	O
filesystem	B-Application
meta-data	O
from	O
file	O
data	O
location	O
;	O
it	O
goes	O
beyond	O
the	O
simple	O
name/data	O
separation	O
by	O
striping	O
the	O
data	O
amongst	O
a	O
set	O
of	O
data	O
servers	O
.	O
</s>
<s>
This	O
differs	O
from	O
the	O
traditional	O
NFS	O
server	B-Application
which	O
holds	O
the	O
names	O
of	O
files	O
and	O
their	O
data	O
under	O
the	O
single	O
umbrella	O
of	O
the	O
server	B-Application
.	O
</s>
<s>
Some	O
products	O
are	O
multi-node	O
NFS	O
servers	O
,	O
but	O
the	O
participation	O
of	O
the	O
client	B-Protocol
in	O
separation	O
of	O
meta-data	O
and	O
data	O
is	O
limited	O
.	O
</s>
<s>
The	O
NFSv4.1	O
pNFS	O
server	B-Application
is	O
a	O
set	O
of	O
server	B-Application
resources	O
or	O
components	O
;	O
these	O
are	O
assumed	O
to	O
be	O
controlled	O
by	O
the	O
meta-data	O
server	B-Application
.	O
</s>
<s>
The	O
pNFS	O
client	B-Protocol
still	O
accesses	O
one	O
meta-data	O
server	B-Application
for	O
traversal	O
or	O
interaction	O
with	O
the	O
namespace	O
;	O
when	O
the	O
client	B-Protocol
moves	O
data	O
to	O
and	O
from	O
the	O
server	B-Application
it	O
may	O
directly	O
interact	O
with	O
the	O
set	O
of	O
data	O
servers	O
belonging	O
to	O
the	O
pNFS	O
server	B-Application
collection	O
.	O
</s>
<s>
The	O
NFSv4.1	O
client	B-Protocol
can	O
be	O
enabled	O
to	O
be	O
a	O
direct	O
participant	O
in	O
the	O
exact	O
location	O
of	O
file	O
data	O
and	O
to	O
avoid	O
solitary	O
interaction	O
with	O
one	O
NFS	O
server	B-Application
when	O
moving	O
data	O
.	O
</s>
