NFSD(8)                 FreeBSD System Manager's Manual                NFSD(8)

NAME
     nfsd - remote NFS server

SYNOPSIS
     nfsd [-ardute] [-n num_servers] [-h bindip] [-p pnfs_setup]
          [-m mirror_level] [-V virtual_hostname] [--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.

     -V virtual_hostname
             Specifies a hostname to be used as a principal name, instead of
             the default hostname.

     -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.

     -p pnfs_setup
             Enables pNFS support in the server and specifies the information
             that the daemon needs to start it.  This option can only be used
             on one server and specifies that this server will be the MetaData
             Server (MDS) for the pNFS service.  This can only be done if
             there is at least one FreeBSD system configured as a Data Server
             (DS) for it to use.

             The pnfs_setup string is a set of fields separated by ','
             characters: Each of these fields specifies one DS.  It consists
             of a server hostname, followed by a ':' and the directory path
             where the DS's data storage file system is mounted on this MDS
             server.  This can optionally be followed by a '#' and the
             mds_path, which is the directory path for an exported file system
             on this MDS.  If this is specified, it means that this DS is to
             be used to store data files for this mds_path file system only.
             If this optional component does not exist, the DS will be used to
             store data files for all exported MDS file systems.  The DS
             storage file systems must be mounted on this system before the
             nfsd is started with this option specified.
             For example:

             nfsv4-data0:/data0,nfsv4-data1:/data1

             would specify two DS servers called nfsv4-data0 and nfsv4-data1
             that comprise the data storage component of the pNFS service.
             These two DSs would be used to store data files for all exported
             file systems on this MDS.  The directories "/data0" and "/data1"
             are where the data storage servers exported storage directories
             are mounted on this system (which will act as the MDS).
             Whereas, for the example:

             nfsv4-data0:/data0#/export1,nfsv4-data1:/data1#/export2

             would specify two DSs as above, however nfsv4-data0 will be used
             to store data files for "/export1" and nfsv4-data1 will be used
             to store data files for "/export2".

             When using IPv6 addresses for DSs be wary of using link local
             addresses.  The IPv6 address for the DS is sent to the client and
             there is no scope zone in it.  As such, a link local address may
             not work for a pNFS client to DS TCP connection.  When parsed,
             nfsd will only use a link local address if it is the only address
             returned by getaddrinfo(3) for the DS hostname.

     -m mirror_level
             This option is only meaningful when used with the -p option.  It
             specifies the "mirror_level", which defines how many of the DSs
             will have a copy of a file's data storage file.  The default of
             one implies no mirroring of data storage files on the DSs.  The
             "mirror_level" would normally be set to 2 to enable mirroring,
             but can be as high as NFSDEV_MAXMIRRORS.  There must be at least
             "mirror_level" DSs for each exported file system on the MDS, as
             specified in the -p option.  This implies that, for the above
             example using "#/export1" and "#/export2", mirroring cannot be
             done.  There would need to be two DS entries for each of
             "#/export1" and "#/export2" in order to support a "mirror_level"
             of two.

             If mirroring is enabled, the server must use the Flexible File
             layout.  If mirroring is not enabled, the server will use the
             File layout by default, but this default can be changed to the
             Flexible File layout if the sysctl(8) vfs.nfsd.default_flexfile
             is set non-zero.

     -t      Serve TCP NFS clients.

     -u      Serve UDP NFS clients.

     -e      Ignored; included for backward compatibility.

     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, Network File System (NFS) Version 4 Protocol,
     RFC7530, Network File System (NFS) Version 4 Minor Version 1 Protocol,
     RFC5661, Network File System (NFS) Version 4 Minor Version 2 Protocol,
     RFC7862, File System Extended Attributes in NFSv4, RFC8276 and Parallel
     NFS (pNFS) Flexible File Layout, RFC8435.

     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), pnfs(4), pnfsserver(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.

     For a Flexible File Layout pNFS server, if there are Linux clients doing
     NFSv4.1 or NFSv4.2 mounts, those clients might need the sysctl(8)
     vfs.nfsd.flexlinuxhack to be set to one on the MDS as a workaround.

     Linux 5.n kernels appear to have been patched such that this sysctl(8)
     does not need to be set.

FreeBSD 13.1-RELEASE-p6        December 20, 2019       FreeBSD 13.1-RELEASE-p6