mount_nfs4(8)

NAME

mount_nfs4 - mount NFSv4 file systems

SYNOPSIS

mount_nfs4 [-biNPsTU] [-a maxreadahead] [-D deadthresh]  [-I
readdirsize]
           [-o  options]  [-R  retrycnt]  [-t  timeout]  [-x
retrans]
           rhost:path node

DESCRIPTION

The mount_nfs4 utility calls the mount(2) system call to

prepare and
graft a remote NFSv4 file system (rhost:path) on to the file

system tree
at the point node. This command is normally executed by

mount(8). It
implements the NFSv4 protocol as described in RFC 3530, NFS

version 4
Protocol.

If the server becomes unresponsive while an NFSv4 file sys

tem is mounted,
any new or outstanding file operations on that file system

will hang
uninterruptibly until the server comes back. To modify this

default
behaviour, see the -i and -s flags.

The options are:

-D Set the ``dead server threshold'' to the specified

number of

round trip timeout intervals before a ``server not

responding''
message is displayed.

-I Set the readdir read size to the specified value.

The value

should normally be a multiple of DIRBLKSIZ that is

<= the read
size for the mount.

-N Do not use a reserved socket port number (see be

low).

-P Use a reserved socket port number. This flag is ob

solete, and

only retained for compatibility reasons. Reserved

port numbers
are used by default now. (For the rare case where

the client has
a trusted root account but untrustworthy users and

the network
cables are in secure areas this does help, but for

normal desktop
clients this does not apply.)

-R Set the mount retry count to the specified value.

The default is

a retry count of zero, which means to keep retrying

forever.
There is a 60 second delay between each attempt.

-T Use TCP transport. This is the default.

-U Force the mount protocol to use UDP transport. This

is not sup

ported by the version 4 protocol and is provided on

ly for debugging purposes.

-a Set the read-ahead count to the specified value.

This may be in

the range of 0 - 4, and determines how many blocks

will be read
ahead when a large file is being read sequentially.

Trying a
value greater than 1 for this is suggested for

mounts with a
large bandwidth * delay product.

-b If an initial attempt to contact the server fails,

fork off a

child to keep trying the mount in the background.

Useful for
fstab(5), where the file system mount is not criti

cal to multiuser operation.

-i Make the mount interruptible, which implies that

file system

calls that are delayed due to an unresponsive server

will fail
with EINTR when a termination signal is posted for

the process.

-o Options are specified with a -o flag followed by a

comma sepa

rated string of options. See the mount(8) man page

for possible
options and their meanings. The following NFS spe

cific options
are also available:

port=<port_number>

Use specified port number for NFSv4 re

quests. The
default is to use port 2049. Set this to 0

to query the
portmapper for the NFSv4 port.

acregmin=<seconds>
acregmax=<seconds>
acdirmin=<seconds>
acdirmax=<seconds>

When attributes of files are cached, a time

out calculated
to determine whether a given cache entry has

expired.
These four values determine the upper and

lower bounds of
the timeouts for ``directory'' attributes

and ``regular''
(i.e., everything else). The default values

are 3 -> 60
seconds for regular files, and 30 -> 60 sec

onds for
directories. The algorithm to calculate the

timeout is
based on the age of the file. The older the

file, the
longer the cache is considered valid, sub

ject to the limits above.

noinet4, noinet6

Disables AF_INET or AF_INET6 connections.

Useful for
hosts that have both an A record and an AAAA

record for
the same name.

-s A soft mount, which implies that file system calls

will fail

after retrycnt round trip timeout intervals.

-t Set the initial retransmit timeout to the specified

value. May

be useful for fine tuning UDP mounts over internet

works with high
packet loss rates or an overloaded server. Try in

creasing the
interval if nfsstat(1) shows high retransmit rates

while the file
system is active or reducing the value if there is a

low retransmit rate but long response delay observed. (Normal

ly, the -d
option should be specified when using this option to

manually
tune the timeout interval.)

-x Set the retransmit timeout count for soft mounts to

the specified

value.

SEE ALSO

mount(2), unmount(2), fstab(5), idmapd(8), mount(8),

mount_nfs(8),
nfsd(8), nfsiod(8)

BUGS

This version of the NFSv4 client, while functional, is a

long way from
compliance with RFC 3530. It lacks lock state, reboot re

covery, delegation, GSS, and many other mandatory items from the RFC.

BSD November 14, 2003

BSD