nfsd(1M)

NAME

nfsd, biod — NFS daemons

SYNOPSIS

/usr/sbin/nfsd [ -a ] [ -p protocol ] [ -t device ] [num_nfsd]

/usr/sbin/biod [num_nfsiod]

DESCRIPTION

nfsd starts the NFS server daemons that handle client file system requests (see nfs(7)). num_nfsd is the suggested number of file system request daemons that will start. One daemon will be started to support the kernel threads servicing TCP requests, and multiple additional daemons will be started to service UDP requests. At system boot time, num_nfsd is defined by the NUM_NFSD variable in the /etc/rc.config.d/nfsconf file. When the UDP nfsds are launched, the kernel will automatically round up num_nfsd to be a multiple of the number of active CPU's in the system.

A previously invoked nfsd daemon started with or without options must be stopped before invoking another nfsd command.

biod starts num_nfsiod asynchronous block I/O daemons. These daemons are used on the NFS client to improve I/O performance by caching asynchronous read-ahead and write-behind requests. At system boot time, num_nfsiod is defined by the NUM_NFSIOD variable in the /etc/rc.config.d/nfsconf file. The number of active CPU's on the system does not affect the number of biod daemons started.

Options

nfsd recognizes the following options:

-a: Start a NFS daemon over all supported connectionless and connection-oriented transports, including UDP and TCP.
-p protocol: Start a NFS daemon over the specified protocol.
-t device: Start a NFS daemon for the transport specified by the given device.
num_nfsd: num_nfsd is the suggested number of file system request daemons that will start. The actual number of daemons started will be one daemon to support kernel TCP threads plus a number of UDP daemons. The number of UDP daemons started will be the value of num_nfsd rounded up to a multiple of the number of active CPU's in the system.

biod recognizes the following options:

num_nfsiod: num_nfsiod is the number of asynchronous block I/O daemons that will start. The number of active CPU's in the system does not affect the number of biod daemons started.

Application Usage

If the nfs_portmon variable is set to 1, then clients are required to use privileged ports (ports < IPPORT_RESERVED) in order to get NFS services. The default value of nfs_portmon on HP-UX systems is 0.

To set the variable, execute the following command on the target system:

kctune nfs_portmon=1 

To unset the variable, execute the following command on the target system:

kctune nfs_portmon=0 

EXAMPLES

On a system with 16 active CPU's the following command:

/usr/sbin/nfsd 30 

will result in a total 33 nfsds being launched. For UDP requests, the kernel rounds-up the requested num_nfsd value to be a multiple of the number of active CPU's in the system, resulting in 32 UDP daemons. One additional daemon will be launched to support kernel TCP threads, resulting in a total of 33 daemons.

The following command:

/usr/sbin/biod 16 

will result in a total of 16 block I/O daemons being launched. The number of active CPU's in the system has no effect on the number of biod daemons started.

WARNINGS

When the biod daemons are not running and the buffer cache is exhausted, I/O on NFS loopback file systems might block indefinitely under rare circumstances, leading to application hangs. To avoid such a problem, it is recommended to use direct I/O on these NFS mounts (see mount_nfs(1M)).

AUTHOR

nfsd was developed by Sun Microsystems, Inc.

nfsd(1M)

Technical documentation

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