4.4BSD/usr/share/man/cat8/mount_nfs.0
MOUNT_NFS(8) BSD System Manager's Manual MOUNT_NFS(8)
NNAAMMEE
mmoouunntt__nnffss - mount nfs file systems
SSYYNNOOPPSSIISS
mmoouunntt__nnffss [--bbssiiTTMMllqqddcckkPPKK] [--RR _r_e_t_r_y_c_n_t] [--rr _r_e_a_d_s_i_z_e] [--ww _w_r_i_t_e_s_i_z_e] [--tt
_t_i_m_e_o_u_t] [--xx _r_e_t_r_a_n_s] [--gg _m_a_x_g_r_o_u_p_s] [--aa _m_a_x_r_e_a_d_a_h_e_a_d] [--LL
_l_e_a_s_e_t_e_r_m] [--DD _d_e_a_d_t_h_r_e_s_h] [--mm _r_e_a_l_m] _r_h_o_s_t_:_p_a_t_h _n_o_d_e
DDEESSCCRRIIPPTTIIOONN
The mmoouunntt__nnffss command calls the mount(2) system call to prepare and graft
a remote nfs file system (rhost:path) on to the file system tree at the
point _n_o_d_e_. This command is normally executed by mount(8) setting the op-
tions with the --oo flag. It implements the mount protocol as described in
RFC 1094, Appendix A.
The options are:
--bb 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 filesystem mount is not critical to multiuser
operation.
--ss A soft mount, which implies that file system calls will fail af-
ter RReettrryy round trip timeout intervals.
--ii An interruptible mount, 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.
--TT Use TCP transport instead of UDP. This is recommended for
servers that are not on the same LAN cable as the client. (NB:
This is NOT supported by most non-BSD servers.)
--MM Assume that other clients are not writing a file concurrently
with this client. This implements a slightly less strict consis-
tency criteria than 4.3BSD Reno did, that is more in line with
most commercial client implementations. This is recommended for
servers that do not support leasing.
--dd Do not estimate retransmit timeout dynamically. This may be use-
ful for UDP mounts that exhibit high retry rates.
--cc For UDP mount points, do not do a connect(2.) This must be used
for servers that do not reply to requests from the standard port
number.
--PP Use a reserved socket port number. This is useful for mounting
servers that require clients to use a reserved port number.
--KK Pass Kerberos authenticators to the server for client-to-server
user-credential mapping. This may only be used over TCP mounts
between 4.4BSD clients and servers.
--qq Use the leasing extensions to the protocol to maintain cache con-
sistency. This protocol, referred to as Not Quite Nfs (NQNFS),
is only supported by 4.4BSD servers.
--ll Used with NQNFS to specify that the RReeaaddddiirr__aanndd__LLooookkuupp RPC should
be used. This option reduces RPC traffic for cases such as ``ls
-l'', but increases the lease load on the server. This is recom-
mended unless the server is complaining about excessive lease
load.
--kk Used with NQNFS to specify ``get a lease'' for the file name be-
ing looked up. This is recommended unless the server is com-
plaining about excessive lease load.
The following arguments take a value parameter that is either a decimal
number or a character string specified as =<value> after the option flag.
--RR Set the retry count for doing the mount to <value>.
--xx Set the retransmit timeout count for soft mounts to <value>.
--rr Set the read data size to <value>. It should be a power of 2
greater than 512. This should be used for UDP mounts when the
``fragments dropped due to timeout'' value is getting large while
actively using a mount point. (Use netstat(1) with the option to
see what the ``fragments dropped due to timeout'' value is.)
--ww Set the write data size to <value>. Ditto the comments w.r.t.
the --rr option, but using the ``fragments dropped due to timeout''
value on the server instead of the client. Note that both the --rr
and --ww options should only be used as a last ditch effort at im-
proving performance when mounting servers that do not support TCP
mounts.
--tt Set the initial retransmit timeout to <value>. May be useful for
fine tuning UDP mounts over internetworks with high packet loss
rates or an overloaded server. Try increasing 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.
--gg Set the maximum size of the group list for the credentials to
<value>. This should be used for mounts on old servers that can-
not handle a group list size of 16, as specified in RFC 1057.
Try 8, if users in a lot of groups cannot get response from the
mount point.
--aa Set the read-ahead count to <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. This is recommended for
mounts with a large bandwidth * delay product.
--LL Used with NQNFS to set the lease term to <value> seconds. Only
use this argument for mounts with a large round trip delay. Val-
ues are normally in the 10-30 second range.
--DD Used with NQNFS to set the ``dead server threshold'' to <value>
round trip timeout intervals. After a ``dead server threshold''
of retransmit timeouts, cached data for the unresponsive server
is assumed to still be valid. Values may be set in the range of
1 - 9, with 9 referring to an ``infinite dead threshold'' (i.e.
never assume cached data still valid). This option is not gener-
ally recommended and is really an experimental feature.
--mm Set the Kerberos realm to the string argument. Used with the --KK
option for mounts to other realms.
SSEEEE AALLSSOO
mount(2), unmount(2), fstab(5)
BBUUGGSS
Due to the way that Sun RPC is implemented on top of UDP (unreliable
datagram) transport, tuning such mounts is really a black art that can
only be expected to have limited success. For clients mounting servers
that are not on the same LAN cable or that tend to be overloaded, TCP
transport is strongly recommended, but unfortunately this is restricted
to mostly 4.4BSD servers.
4.4BSD June 5, 1993 3