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1fd129c9ff
Include references to NFSv4.2 and associated RFCs. Also clarify when a Linux client needs to set vfs.nfsd.flexlinuxhack if a pNFS server is in use. This is a content change.
342 lines
10 KiB
Groff
342 lines
10 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)nfsd.8 8.4 (Berkeley) 3/29/95
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.\" $FreeBSD$
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.\"
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.Dd December 20, 2019
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.Dt NFSD 8
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.Os
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.Sh NAME
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.Nm nfsd
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.Nd remote
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NFS server
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.Sh SYNOPSIS
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.Nm
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.Op Fl ardute
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.Op Fl n Ar num_servers
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.Op Fl h Ar bindip
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.Op Fl p Ar pnfs_setup
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.Op Fl m Ar mirror_level
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.Op Fl V Ar virtual_hostname
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.Op Fl Fl maxthreads Ar max_threads
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.Op Fl Fl minthreads Ar min_threads
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.Sh DESCRIPTION
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The
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.Nm
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utility runs on a server machine to service NFS requests from client machines.
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At least one
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.Nm
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must be running for a machine to operate as a server.
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.Pp
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Unless otherwise specified, eight servers per CPU for UDP transport are
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started.
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.Pp
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The following options are available:
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.Bl -tag -width Ds
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.It Fl r
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Register the NFS service with
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.Xr rpcbind 8
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without creating any servers.
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This option can be used along with the
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.Fl u
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or
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.Fl t
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options to re-register NFS if the rpcbind server is restarted.
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.It Fl d
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Unregister the NFS service with
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.Xr rpcbind 8
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without creating any servers.
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.It Fl V Ar virtual_hostname
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Specifies a hostname to be used as a principal name, instead of
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the default hostname.
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.It Fl n Ar threads
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Specifies how many servers to create.
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This option is equivalent to specifying
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.Fl Fl maxthreads
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and
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.Fl Fl minthreads
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with their respective arguments to
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.Ar threads .
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.It Fl Fl maxthreads Ar threads
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Specifies the maximum servers that will be kept around to service requests.
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.It Fl Fl minthreads Ar threads
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Specifies the minimum servers that will be kept around to service requests.
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.It Fl h Ar bindip
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Specifies which IP address or hostname to bind to on the local host.
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This option is recommended when a host has multiple interfaces.
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Multiple
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.Fl h
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options may be specified.
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.It Fl a
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Specifies that nfsd should bind to the wildcard IP address.
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This is the default if no
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.Fl h
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options are given.
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It may also be specified in addition to any
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.Fl h
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options given.
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Note that NFS/UDP does not operate properly when
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bound to the wildcard IP address whether you use -a or do not use -h.
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.It Fl p Ar pnfs_setup
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Enables pNFS support in the server and specifies the information that the
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daemon needs to start it.
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This option can only be used on one server and specifies that this server
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will be the MetaData Server (MDS) for the pNFS service.
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This can only be done if there is at least one
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.Fx
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system configured
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as a Data Server (DS) for it to use.
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.Pp
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The
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.Ar pnfs_setup
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string is a set of fields separated by ',' characters:
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Each of these fields specifies one DS.
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It consists of a server hostname, followed by a ':'
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and the directory path where the DS's data storage file system is mounted on
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this MDS server.
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This can optionally be followed by a '#' and the mds_path, which is the
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directory path for an exported file system on this MDS.
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If this is specified, it means that this DS is to be used to store data
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files for this mds_path file system only.
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If this optional component does not exist, the DS will be used to store data
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files for all exported MDS file systems.
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The DS storage file systems must be mounted on this system before the
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.Nm
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is started with this option specified.
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.br
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For example:
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.sp
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nfsv4-data0:/data0,nfsv4-data1:/data1
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.sp
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would specify two DS servers called nfsv4-data0 and nfsv4-data1 that comprise
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the data storage component of the pNFS service.
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These two DSs would be used to store data files for all exported file systems
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on this MDS.
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The directories
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.Dq /data0
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and
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.Dq /data1
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are where the data storage servers exported
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storage directories are mounted on this system (which will act as the MDS).
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.br
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Whereas, for the example:
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.sp
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nfsv4-data0:/data0#/export1,nfsv4-data1:/data1#/export2
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.sp
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would specify two DSs as above, however nfsv4-data0 will be used to store
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data files for
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.Dq /export1
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and nfsv4-data1 will be used to store data files for
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.Dq /export2 .
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.sp
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When using IPv6 addresses for DSs
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be wary of using link local addresses.
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The IPv6 address for the DS is sent to the client and there is no scope
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zone in it.
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As such, a link local address may not work for a pNFS client to DS
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TCP connection.
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When parsed,
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.Nm
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will only use a link local address if it is the only address returned by
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.Xr getaddrinfo 3
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for the DS hostname.
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.It Fl m Ar mirror_level
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This option is only meaningful when used with the
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.Fl p
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option.
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It specifies the
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.Dq mirror_level ,
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which defines how many of the DSs will
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have a copy of a file's data storage file.
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The default of one implies no mirroring of data storage files on the DSs.
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The
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.Dq mirror_level
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would normally be set to 2 to enable mirroring, but
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can be as high as NFSDEV_MAXMIRRORS.
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There must be at least
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.Dq mirror_level
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DSs for each exported file system on the MDS, as specified in the
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.Fl p
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option.
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This implies that, for the above example using "#/export1" and "#/export2",
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mirroring cannot be done.
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There would need to be two DS entries for each of "#/export1" and "#/export2"
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in order to support a
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.Dq mirror_level
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of two.
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.Pp
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If mirroring is enabled, the server must use the Flexible File
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layout.
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If mirroring is not enabled, the server will use the File layout
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by default, but this default can be changed to the Flexible File layout if the
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.Xr sysctl 8
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vfs.nfsd.default_flexfile
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is set non-zero.
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.It Fl t
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Serve TCP NFS clients.
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.It Fl u
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Serve UDP NFS clients.
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.It Fl e
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Ignored; included for backward compatibility.
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.El
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.Pp
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For example,
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.Dq Li "nfsd -u -t -n 6"
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serves UDP and TCP transports using six daemons.
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.Pp
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A server should run enough daemons to handle
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the maximum level of concurrency from its clients,
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typically four to six.
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.Pp
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The
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.Nm
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utility listens for service requests at the port indicated in the
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NFS server specification; see
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.%T "Network File System Protocol Specification" ,
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RFC1094,
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.%T "NFS: Network File System Version 3 Protocol Specification" ,
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RFC1813,
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.%T "Network File System (NFS) Version 4 Protocol" ,
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RFC7530,
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.%T "Network File System (NFS) Version 4 Minor Version 1 Protocol" ,
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RFC5661,
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.%T "Network File System (NFS) Version 4 Minor Version 2 Protocol" ,
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RFC7862,
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.%T "File System Extended Attributes in NFSv4" ,
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RFC8276 and
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.%T "Parallel NFS (pNFS) Flexible File Layout" ,
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RFC8435.
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.Pp
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If
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.Nm
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detects that
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NFS is not loaded in the running kernel, it will attempt
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to load a loadable kernel module containing NFS support using
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.Xr kldload 2 .
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If this fails, or no NFS KLD is available,
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.Nm
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will exit with an error.
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.Pp
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If
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.Nm
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is to be run on a host with multiple interfaces or interface aliases, use
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of the
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.Fl h
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option is recommended.
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If you do not use the option NFS may not respond to
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UDP packets from the same IP address they were sent to.
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Use of this option
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is also recommended when securing NFS exports on a firewalling machine such
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that the NFS sockets can only be accessed by the inside interface.
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The
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.Nm ipfw
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utility
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would then be used to block NFS-related packets that come in on the outside
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interface.
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.Pp
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If the server has stopped servicing clients and has generated a console message
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like
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.Dq Li "nfsd server cache flooded..." ,
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the value for vfs.nfsd.tcphighwater needs to be increased.
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This should allow the server to again handle requests without a reboot.
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Also, you may want to consider decreasing the value for
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vfs.nfsd.tcpcachetimeo to several minutes (in seconds) instead of 12 hours
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when this occurs.
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.Pp
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Unfortunately making vfs.nfsd.tcphighwater too large can result in the mbuf
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limit being reached, as indicated by a console message
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like
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.Dq Li "kern.ipc.nmbufs limit reached" .
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If you cannot find values of the above
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.Nm sysctl
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values that work, you can disable the DRC cache for TCP by setting
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vfs.nfsd.cachetcp to 0.
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.Pp
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The
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.Nm
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utility has to be terminated with
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.Dv SIGUSR1
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and cannot be killed with
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.Dv SIGTERM
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or
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.Dv SIGQUIT .
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The
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.Nm
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utility needs to ignore these signals in order to stay alive as long
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as possible during a shutdown, otherwise loopback mounts will
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not be able to unmount.
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If you have to kill
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.Nm
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just do a
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.Dq Li "kill -USR1 <PID of master nfsd>"
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.Sh EXIT STATUS
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.Ex -std
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.Sh SEE ALSO
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.Xr nfsstat 1 ,
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.Xr kldload 2 ,
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.Xr nfssvc 2 ,
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.Xr nfsv4 4 ,
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.Xr pnfs 4 ,
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.Xr pnfsserver 4 ,
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.Xr exports 5 ,
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.Xr stablerestart 5 ,
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.Xr gssd 8 ,
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.Xr ipfw 8 ,
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.Xr mountd 8 ,
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.Xr nfsiod 8 ,
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.Xr nfsrevoke 8 ,
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.Xr nfsuserd 8 ,
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.Xr rpcbind 8
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Bx 4.4 .
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.Sh BUGS
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If
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.Nm
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is started when
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.Xr gssd 8
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is not running, it will service AUTH_SYS requests only.
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To fix the problem you must kill
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.Nm
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and then restart it, after the
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.Xr gssd 8
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is running.
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.Pp
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For a Flexible File Layout pNFS server,
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if there are Linux clients doing NFSv4.1 or NFSv4.2 mounts, those
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clients might need the
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.Xr sysctl 8
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vfs.nfsd.flexlinuxhack
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to be set to one on the MDS as a workaround.
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.Pp
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Linux 5.n kernels appear to have been patched such that this
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.Xr sysctl 8
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does not need to be set.
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