table of contents
NFSD(8) | System Manager's Manual | NFSD(8) |
NAME¶
nfsd
— remote NFS
server
SYNOPSIS¶
nfsd |
[-arduteo ] [-n
num_servers] [-h
bindip] [--maxthreads
max_threads] [--minthreads
min_threads] |
DESCRIPTION¶
The nfsd
utility runs on a server machine
to service NFS requests from client machines. At least one
nfsd
must be running for a machine to operate as a
server.
Unless otherwise specified, eight servers per CPU for UDP transport are started.
The following options are available:
-r
- Register the NFS service with rpcbind(8) without
creating any servers. This option can be used along with the
-u
or-t
options to re-register NFS if the rpcbind server is restarted. -d
- Unregister the NFS service with rpcbind(8) without creating any servers.
-n
threads- Specifies how many servers to create. This option is equivalent to
specifying
--maxthreads
and--minthreads
with their respective arguments to threads. --maxthreads
threads- Specifies the maximum servers that will be kept around to service requests.
--minthreads
threads- Specifies the minimum servers that will be kept around to service requests.
-h
bindip- Specifies which IP address or hostname to bind to on the local host. This
option is recommended when a host has multiple interfaces. Multiple
-h
options may be specified. -a
- Specifies that nfsd should bind to the wildcard IP address. This is the
default if no
-h
options are given. It may also be specified in addition to any-h
options given. Note that NFS/UDP does not operate properly when bound to the wildcard IP address whether you use -a or do not use -h. -t
- Serve TCP NFS clients.
-u
- Serve UDP NFS clients.
-e
- The new NFS server that includes NFSv4 support is now the default, so this option is now a no-op and should be considered deprecated.
-o
- Forces the use of the old NFS server that does not include NFSv4 support in it.
For example, “nfsd -u -t -n
6
” serves UDP and TCP transports using six daemons.
A server should run enough daemons to handle the maximum level of concurrency from its clients, typically four to six.
The nfsd
utility listens for service
requests at the port indicated in the NFS server specification; see
Network File System Protocol Specification,
RFC1094, NFS: Network File System Version 3 Protocol
Specification, RFC1813 and Network File System
(NFS) Version 4 Protocol, RFC3530.
If nfsd
detects that NFS is not loaded in
the running kernel, it will attempt to load a loadable kernel module
containing NFS support using kldload(2). If this fails, or
no NFS KLD is available, nfsd
will exit with an
error.
If nfsd
is to be run on a host with
multiple interfaces or interface aliases, use of the
-h
option is recommended. If you do not use the
option NFS may not respond to UDP packets from the same IP address they were
sent to. Use of this option is also recommended when securing NFS exports on
a firewalling machine such that the NFS sockets can only be accessed by the
inside interface. The ipfw
utility would then be
used to block nfs-related packets that come in on the outside interface.
If the server has stopped servicing clients and has generated a
console message like “nfsd server cache
flooded...
”, the value for vfs.nfsd.tcphighwater needs to be
increased. This should allow the server to again handle requests without a
reboot. Also, you may want to consider decreasing the value for
vfs.nfsd.tcpcachetimeo to several minutes (in seconds) instead of 12 hours
when this occurs.
Unfortunately making vfs.nfsd.tcphighwater too large can result in
the mbuf limit being reached, as indicated by a console message like
“kern.ipc.nmbufs limit reached
”. If
you cannot find values of the above sysctl
values
that work, you can disable the DRC cache for TCP by setting
vfs.nfsd.cachetcp to 0.
The nfsd
utility has to be terminated with
SIGUSR1
and cannot be killed with
SIGTERM
or SIGQUIT
. The
nfsd
utility needs to ignore these signals in order
to stay alive as long as possible during a shutdown, otherwise loopback
mounts will not be able to unmount. If you have to kill
nfsd
just do a “kill -USR1
<PID of master nfsd>
”
EXIT STATUS¶
The nfsd
utility exits 0 on
success, and >0 if an error occurs.
SEE ALSO¶
nfsstat(1), kldload(2), nfssvc(2), nfsv4(4), exports(5), stablerestart(5), gssd(8), ipfw(8), mountd(8), nfsiod(8), nfsrevoke(8), nfsuserd(8), rpcbind(8)
HISTORY¶
The nfsd
utility first appeared in
4.4BSD.
BUGS¶
If nfsd
is started when
gssd(8) is not running, it will service AUTH_SYS requests
only. To fix the problem you must kill nfsd
and then
restart it, after the gssd(8) is running.
January 1, 2015 | Debian |