mount/nfs.5

   1 .\" nfs.5 "Rick Sladkey" <jrs@world.std.com>
   2 .\" Wed Feb  8 12:52:42 1995, faith@cs.unc.edu: updates for Ross Biro's
   3 .\" patches. "
   4 .TH NFS 5 "20 November 1993" "Linux 0.99" "Linux Programmer's Manual"
   5 .SH NAME
   6 nfs \- nfs fstab format and options
   7 .SH SYNOPSIS
   8 .B /etc/fstab
   9 .SH DESCRIPTION
  10 The
  11 .I fstab
  12 file contains information about which filesystems
  13 to mount where and with what options.
  14 For NFS mounts, it contains the server name and
  15 exported server directory to mount from,
  16 the local directory that is the mount point,
  17 and the NFS specific options that control
  18 the way the filesystem is mounted.
  19 .P
  20 Here is an example from an \fI/etc/fstab\fP file from an NFS mount.
  21 .sp
  22 .nf
  23 .ta 2.5i +0.75i +0.75i +1.0i
  24 server:/usr/local/pub   /pub    nfs     rsize=8192,wsize=8192,timeo=14,intr
  25 .fi
  26 .DT
  27 .SS Options
  28 .TP 1.5i
  29 .I rsize=n
  30 The number of bytes NFS uses when reading files from an NFS server.
  31 The default value is dependent on the kernel, currently 1024 bytes.
  32 (However, throughput is improved greatly by asking for
  33 .IR rsize=8192 .)
  34 .TP 1.5i
  35 .I wsize=n
  36 The number of bytes NFS uses when writing files to an NFS server.
  37 The default value is dependent on the kernel, currently 1024 bytes.
  38 (However, throughput is improved greatly by asking for
  39 .IR wsize=8192 .)
  40 .TP 1.5i
  41 .I timeo=n
  42 The value in tenths of a second before sending the
  43 first retransmission after an RPC timeout.
  44 The default value is 7 tenths of a second.  After the first timeout,
  45 the timeout is doubled after each successive timeout until a maximum
  46 timeout of 60 seconds is reached or the enough retransmissions
  47 have occured to cause a major timeout.  Then, if the filesystem
  48 is hard mounted, each new timeout cascade restarts at twice the
  49 initial value of the previous cascade, again doubling at each
  50 retransmission.  The maximum timeout is always 60 seconds.
  51 Better overall performance may be achieved by increasing the
  52 timeout when mounting on a busy network, to a slow server, or through
  53 several routers or gateways.
  54 .TP 1.5i
  55 .I retrans=n
  56 The number of minor timeouts and retransmissions that must occur before
  57 a major timeout occurs.  The default is 3 timeouts.  When a major timeout
  58 occurs, the file operation is either aborted or a "server not responding"
  59 message is printed on the console.
  60 .TP 1.5i
  61 .I acregmin=n
  62 The minimum time in seconds that attributes of a regular file should
  63 be cached before requesting fresh information from a server.
  64 The default is 3 seconds.
  65 .TP 1.5i
  66 .I acregmax=n
  67 The maximum time in seconds that attributes of a regular file can
  68 be cached before requesting fresh information from a server.
  69 The default is 60 seconds.
  70 .TP 1.5i
  71 .I acdirmin=n
  72 The minimum time in seconds that attributes of a directory should
  73 be cached before requesting fresh information from a server.
  74 The default is 30 seconds.
  75 .TP 1.5i
  76 .I acdirmax=n
  77 The maximum time in seconds that attributes of a directory can
  78 be cached before requesting fresh information from a server.
  79 The default is 60 seconds.
  80 .TP 1.5i
  81 .I actimeo=n
  82 Using actimeo sets all of
  83 .I acregmin,
  84 .I acregmax,
  85 .I acdirmin,
  86 and
  87 .I acdirmax
  88 to the same value.
  89 There is no default value.
  90 .TP 1.5i
  91 .I retry=n
  92 The number of minutes to retry an NFS mount operation
  93 in the foreground or background before giving up.
  94 The default value is 10000 minutes, which is roughly one week.
  95 .TP 1.5i
  96 .I namlen=n
  97 When an NFS server does not support version two of the
  98 RPC mount protocol, this option can be used to specify
  99 the maximum length of a filename that is supported on
 100 the remote filesystem.  This is used to support the
 101 POSIX pathconf functions.  The default is 255 characters.
 102 .TP 1.5i
 103 .I port=n
 104 The numeric value of the port to connect to the NFS server on.
 105 If the port number is 0 (the default) then query the
 106 remote host's portmapper for the port number to use.
 107 If the remote host's NFS daemon is not registered with
 108 its portmapper, the standard NFS port number 2049 is
 109 used instead.
 110 .TP 1.5i
 111 .I mountport=n
 112 The numeric value of the
 113 .B mountd
 114 port.
 115 .TP 1.5i
 116 .I mounthost=name
 117 The name of the host running
 118 .B mountd .
 119 .TP 1.5i
 120 .I mountprog=n
 121 Use an alternate RPC program number to contact the
 122 mount daemon on the remote host.  This option is useful
 123 for hosts that can run multiple NFS servers.
 124 The default value is 100005 which is the standard RPC
 125 mount daemon program number.
 126 .TP 1.5i
 127 .I mountvers=n
 128 Use an alternate RPC version number to contact the
 129 mount daemon on the remote host.  This option is useful
 130 for hosts that can run multiple NFS servers.
 131 The default value is version 1.
 132 .TP 1.5i
 133 .I nfsprog=n
 134 Use an alternate RPC program number to contact the
 135 NFS daemon on the remote host.  This option is useful
 136 for hosts that can run multiple NFS servers.
 137 The default value is 100003 which is the standard RPC
 138 NFS daemon program number.
 139 .TP 1.5i
 140 .I nfsvers=n
 141 Use an alternate RPC version number to contact the
 142 NFS daemon on the remote host.  This option is useful
 143 for hosts that can run multiple NFS servers.
 144 The default value is version 2.
 145 .TP 1.5i
 146 .I bg
 147 If the first NFS mount attempt times out, retry the mount
 148 in the background.
 149 After a mount operation is backgrounded, all subsequent mounts
 150 on the same NFS server will be backgrounded immediately, without
 151 first attempting the mount.
 152 A missing mount point is treated as a timeout,
 153 to allow for nested NFS mounts.
 154 .TP 1.5i
 155 .I fg
 156 If the first NFS mount attempt times out, retry the mount
 157 in the foreground.
 158 This is the complement of the
 159 .I bg
 160 option, and also the default behavior.
 161 .TP 1.5i
 162 .I soft
 163 If an NFS file operation has a major timeout then report an I/O error to
 164 the calling program.
 165 The default is to continue retrying NFS file operations indefinitely.
 166 .TP 1.5i
 167 .I hard
 168 If an NFS file operation has a major timeout then report
 169 "server not responding" on the console and continue retrying indefinitely.
 170 This is the default.
 171 .TP 1.5i
 172 .I intr
 173 If an NFS file operation has a major timeout and it is hard mounted,
 174 then allow signals to interupt the file operation and cause it to
 175 return EINTR to the calling program.  The default is to not
 176 allow file operations to be interrupted.
 177 .TP 1.5i
 178 .I posix
 179 Mount the NFS filesystem using POSIX semantics.  This allows
 180 an NFS filesystem to properly support the POSIX pathconf
 181 command by querying the mount server for the maximum length
 182 of a filename.  To do this, the remote host must support version
 183 two of the RPC mount protocol.  Many NFS servers support only
 184 version one.
 185 .TP 1.5i
 186 .I nocto
 187 Suppress the retrieval of new attributes when creating a file.
 188 .TP 1.5i
 189 .I noac
 190 Disable all forms of attribute caching entirely.  This extracts a
 191 server performance penalty but it allows two different NFS clients
 192 to get reasonable good results when both clients are actively
 193 writing to common filesystem on the server.
 194 .TP 1.5i
 195 .I tcp
 196 Mount the NFS filesystem using the TCP protocol instead of the
 197 default UDP protocol.  Many NFS severs only support UDP.
 198 .TP 1.5i
 199 .I udp
 200 Mount the NFS filesystem using the UDP protocol.  This
 201 is the default.
 202 .P
 203 All of the non-value options have corresponding nooption forms.
 204 For example, nointr means don't allow file operations to be
 205 interrupted.
 206 .SH FILES
 207 .I /etc/fstab
 208 .SH "SEE ALSO"
 209 .BR fstab "(5), " mount "(8), " umount "(8), " exports (5)
 210 .SH AUTHOR
 211 "Rick Sladkey" <jrs@world.std.com>
 212 .SH BUGS
 213 The posix, and nocto options are parsed by mount
 214 but currently are silently ignored.
 215 .P
 216 The tcp and namlen options are implemented but are not currently
 217 supported by the Linux kernel.
 218 .P
 219 The umount command should notify the server
 220 when an NFS filesystem is unmounted.