Document the "-p" and "-m" options added to nfsd.c by r335172.

This is a content change.

usr.sbin/nfsd/nfsd.8

@@ -28,7 +28,7 @@
 .\"	@(#)nfsd.8	8.4 (Berkeley) 3/29/95
 .\" $FreeBSD$
 .\"
-.Dd April 25, 2015
+.Dd May 31, 2018
 .Dt NFSD 8
 .Os
 .Sh NAME
@@ -41,6 +41,8 @@ server
 .Op Fl ardute
 .Op Fl n Ar num_servers
 .Op Fl h Ar bindip
+.Op Fl p Ar pnfs_setup
+.Op Fl m Ar mirror_level
 .Op Fl Fl maxthreads Ar max_threads
 .Op Fl Fl minthreads Ar min_threads
 .Sh DESCRIPTION
@@ -103,6 +105,64 @@ It may also be specified in addition to any
 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.
+.It Fl p Ar 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.
+.Pp
+The
+.Ar pnfs_setup
+string is a set of fields separated by ',' characters:
+.Bl -tag -width Ds
+Each of these fields specifies one Data Server.
+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.
+At this time, only IPv4 addresses are supported by the interface to the kernel,
+so the
+.Dq server hostname
+must resolve to an IPv4 address and support mounts on that address.
+This needs to be extended to support IPv6 addresses in the near future.
+The DS storage file systems must be mounted on this system before the
+.Nm
+is started with this option specified.
+For example:
+.sp
+nfsv4-data0:/data0,nfsv4-data1:/data1
+.sp
+Would specify two DS servers called nfsv4-data0 and nfsv4-data1 that comprise
+the data storage component of the pNFS service.
+The directories
+.Dq /data0
+and
+.Dq /data1
+are where the data storage servers exported
+storage directories are mounted on this system (which will act as the MDS).
+.El
+.It Fl m Ar mirror_level
+This option is only meaningful when used with the
+.Fl p
+option.
+It specifies the
+.Dq 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
+.Dq mirror_level
+would normally be set to 2 to enable mirroring, but
+can be as high as NFSDEV_MAXMIRRORS.
+.Pp
+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
+.Xr sysctl 1
+vfs.nfsd.default_flexfile
+is set non-zero.
 .It Fl t
 Serve
 .Tn TCP NFS
@@ -135,9 +195,11 @@ server specification; see
 .%T "Network File System Protocol Specification" ,
 RFC1094,
 .%T "NFS: Network File System Version 3 Protocol Specification" ,
-RFC1813 and
+RFC1813,
 .%T "Network File System (NFS) Version 4 Protocol" ,
-RFC3530.
+RFC3530 and
+.%T "Network File System (NFS) Version 4 Minor Version 1 Protocol" ,
+RFC5661.
 .Pp
 If
 .Nm
@@ -213,6 +275,7 @@ just do a
 .Xr kldload 2 ,
 .Xr nfssvc 2 ,
 .Xr nfsv4 4 ,
+.Xr pnfs 4 ,
 .Xr exports 5 ,
 .Xr stablerestart 5 ,
 .Xr gssd 8 ,
@@ -238,3 +301,14 @@ you must kill
 and then restart it, after the
 .Xr gssd 8
 is running.
+.Pp
+If mirroring is enabled via the
+.Fl m
+option and there are Linux clients doing NFSv4.1 mounts, those clients
+need to be patched to support the
+.Dq tightly coupled
+variant of
+the Flexible File layout or the
+.Xr sysctl 1
+vfs.nfsd.flexlinuxhack
+must be set to one on the MDS as a workaround.