nfsd(1M)                                                              nfsd(1M)


NAME
     nfsd, biod, bio3d - NFS daemons

SYNOPSIS
     /usr/etc/nfsd [ -a ] [ -p proto ] [ -c nconns ] [ nservers ]
     /usr/etc/biod [ nclients ]

DESCRIPTION
     nfsd starts the nfs(4) server daemons that handle client NFS requests.

     biod starts asynchronous block I/O daemons.  This command is used on a
     NFS client to perform buffer cache read-ahead and write-behind.

     bio3d processes are the asynchronous kernel processes for NFS version 3.
     No daemon is necessary to start bio3ds.  There is one bio3d associated
     with each mounted filesystem at mount time.  If the NFS traffic to a
     filesystem increases, up to three more bio3d processes are spawned for
     that filesystem.  When traffic subsides, these extra processes exit.

OPTIONS
     -a          Allow the NFS server daemon to service client requests over
                 both the UDP and TCP protocols.  This is the default.

     -p proto    Allow the NFS server daemon to service client requests over
                 either the UDP or the TCP protocols.  The -a option overrides
                 this selection.

     -c nconns   Set an upper limit on the number of simultaneous TCP
                 connections the NFS server has open.  By default this number
                 is 10000.  nconns can be equated with the total number of
                 clients mounting files from this server over TCP; it has no
                 effect on clients mounting over UDP.

     nservers    This is the number of NFS server daemons to start.  From
                 6.5.22 the IRIX kernel manages NFS server daemons dynamically
                 according to load; specifying a number will most likely
                 result in reduced performance. See DYNAMIC NFS DAEMONS below.

     nclients    The number of asynchronous block I/O daemons.  A good number
                 for nclients is 4.  The default is 1.

     These daemons are started during system initialization from the
     /etc/init.d/network script if the configuration flag nfs is set on (see
     network(1M)).

DYNAMIC NFS DAEMONS
     From IRIX 6.5.22, the IRIX kernel NFS service can operate in one of two
     modes, depending on the options passed to nfsd.

     The first mode is the pre-6.5.22 behavior, in which the nservers argument
     to nfsd controls the number of NFS daemons available to handle NFS calls.
     In this mode, a fixed number of daemons is used regardless of NFS load.


     A single number chosen by the system administrator must cater for both
     low-load and high-load conditions.  The usual result is a compromise
     number whereby NFS performance suffers under high-load conditions and
     system resources are wasted in low-load conditions.

     When the nservers argument is given to nfsd, IRIX reverts to this old
     mode, but issues a warning to the system log.

     In the second mode, the IRIX kernel dynamically manages NFS daemons
     depending on the load of NFS traffic the machine is serving.  Daemons are
     spawned and killed as load increases and decreases.  This removes the
     need for the system administrator to tune the number of NFS daemons using
     the nservers argument.

     Previous versions of this manpage and other SGI documents discussed the
     tuning of the number of servers with an emphasis on reducing the number
     of servers to limit resource wastage in low-load or steady-state
     conditions.  This has unfortunately lead to many IRIX systems being
     under-configured for steady high-load conditions or load peaks, resulting
     in poor NFS performance at those times.

     For IRIX systems at 6.5.22 or above, the recommended configuration is to
     enable the new dynamic mode by removing any nservers argument from
     /etc/config/nfsd.options.  This configuration can be expected to deliver
     both optimal NFS performance under high-load conditions and minimal
     resource usage in low-load conditions.  This configuration is shipped as
     the factory default.

     The new dynamic daemon mode is controlled by dynamic system tunables
     rather than arguments to nfsd.  This enables the system administrator to
     change aspects of the dynamic daemon behaviour without the interruption
     in NFS service resulting from killing and restarting the nfsd daemons.
     See the systune(1m) manpage and the comments in /var/sysgen/mtune/oncrpc.

Trusted IRIX (TRIX) LIMITATIONS
     On TRIX systems, NFS over TCP is unsupported. For IRIX versions 6.5.29
     and earlier, it is recommended on systems running TRIX, that in order to
     ensure that NFS runs over UDP, the "-p UDP" option is invoked when nfsd
     is started. For IRIX 6.5.30 systems running TRIX, nfsd facilitates NFS
     over UDP by default, in lieu of the unsupported NFS over TCP.

FILES
     When a file that is opened by a client is unlinked (by the server), a
     file with a name of the form .nfsXXX (where XXX is a number) is created
     by the client.  When the open file is closed, the .nfsXXX file is
     removed.  If the client crashes before the file can be closed, the
     .nfsXXX file is not removed.

FILES
     .nfsXXX     client machine pointer to an open-but-unlinked file


     /etc/config/nfsd.options
                 Site configuration file containing options for nfsd.

     /etc/config/biod.options
                 Site configuration file containing options for biod.

SEE ALSO
     exportfs(1M), mountd(1M), network(1M), systune(1M), exports(4).


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