nbd-server.1.sgml

   1 <!doctype refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN" [
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   3 <!-- Process this file with docbook-to-man to generate an nroff manual
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  11
  12   <!-- Fill in your name for FIRSTNAME and SURNAME. -->
  13   <!ENTITY dhfirstname "<firstname>Wouter</firstname>">
  14   <!ENTITY dhsurname   "<surname>Verhelst</surname>">
  15   <!-- Please adjust the date whenever revising the manpage. -->
  16   <!ENTITY dhdate      "<date>$Date: 2007-06-13 12:07:26 +0100 (wo, 13 jun 2007) $</date>">
  17   <!-- SECTION should be 1-8, maybe w/ subsection other parameters are
  18        allowed: see man(7), man(1). -->
  19   <!ENTITY dhsection   "<manvolnum>1</manvolnum>">
  20   <!ENTITY dhemail     "<email>wouter@debian.org</email>">
  21   <!ENTITY dhusername  "Wouter Verhelst">
  22   <!ENTITY dhucpackage "<refentrytitle>NBD-SERVER</refentrytitle>">
  23   <!ENTITY dhpackage   "nbd-server">
  24
  25   <!ENTITY debian      "<productname>Debian GNU/Linux</productname>">
  26   <!ENTITY gnu         "<acronym>GNU</acronym>">
  27 ]>
  28
  29 <refentry>
  30   <refentryinfo>
  31     <address>
  32       &dhemail;
  33     </address>
  34     <author>
  35       &dhfirstname;
  36       &dhsurname;
  37     </author>
  38     <copyright>
  39       <year>2001</year>
  40       <holder>&dhusername;</holder>
  41     </copyright>
  42     &dhdate;
  43   </refentryinfo>
  44   <refmeta>
  45     &dhucpackage;
  46
  47     &dhsection;
  48   </refmeta>
  49   <refnamediv>
  50     <refname>&dhpackage;</refname>
  51
  52     <refpurpose>serve a file as a block device to other computers
  53     running the &gnu;/Linux(tm) or &gnu;/Hurd Operating
  54     System</refpurpose>
  55   </refnamediv>
  56   <refsynopsisdiv>
  57     <cmdsynopsis>
  58       <command>&dhpackage; </command>
  59
  60       <arg choice=plain><replaceable>port</replaceable</arg>
  61       <arg choice=plain><replaceable>filename</replaceable></arg>
  62       <arg><replaceable>size</replaceable></arg>
  63       <arg><option>-r</option></arg>
  64       <arg><option>-m</option></arg>
  65       <arg><option>-c</option></arg>
  66       <arg><option>-a <replaceable>timeout</replaceable></option></arg>
  67       <arg><option>-l <replaceable>host list</replaceable></option></arg>
  68       <arg><option>-o <replaceable>section name</replaceable></option></arg>
  69     </cmdsynopsis>
  70   </refsynopsisdiv>
  71   <refsect1>
  72     <title>DESCRIPTION</title>
  73
  74     <para><command>&dhpackage;</command> is the server for the Linux
  75     Network Block Device (NBD). With NBD, a client can use a file,
  76     exported over the network from a server, as a block device. It can
  77     then be used for whatever purpose a normal block device (harddisk,
  78     CD-ROM, ...) can be used for.</para>
  79
  80     <para>NBD can be useful for diskless clients that need swapspace,
  81     but you can also create a filesystem on it and use it as though it
  82     were a local filesystem.</para>
  83
  84     <para><command>&dhpackage;</command> implements some security
  85     through a file called "nbd_server.allow" in the current directory (by default; a different file can be chosen with the '-l' option).
  86     This file must list the IP-addresses of clients that are allowed
  87     to connect. If it does not exist, all clients are able to connect.
  88     If the file is empty, no clients can connect.</para>
  89   </refsect1>
  90   <refsect1>
  91     <title>OPTIONS</title>
  92
  93     <variablelist>
  94       <varlistentry>
  95         <term><option>port</option>
  96         </term>
  97         <listitem>
  98           <para>The port the server should listen to. A valid port is
  99             any number between 1 and 65536; if 0 is used, nbd-server
 100             will listen on stdin (so that nbd-server can be ran from
 101             inetd)</para>
 102         </listitem>
 103       </varlistentry>
 104       <varlistentry>
 105         <term><option>filename</option></term>
 106         <listitem>
 107           <para>The filename of the file that should be exported. This
 108           can be any file, including "real" blockdevices (i.e. a file
 109           from /dev). If the filename includes the literal string
 110           "%s", then this %s will be substituded with the IP-address
 111           of the client trying to connect.</para>
 112         </listitem>
 113       </varlistentry>
 114       <varlistentry>
 115         <term><option>size</option></term>
 116         <listitem>
 117           <para>The size of the block device at the client side. This
 118             is especially usefull in conjunction with the -m
 119             option</para>
 120           <para>Can optionally be followed by one of K,k,M or
 121             m, in which case the size will be multiplied by 1024 (K
 122             or k) or 1048576 (M or m)</para>
 123         </listitem>
 124       </varlistentry>
 125       <varlistentry>
 126         <term><option>-r</option></term>
 127         <listitem>
 128           <para>Export the file read-only. If a client tries to write
 129             to a read-only exported file, it will receive an error, but
 130             the connection will stay up.</para>
 131         </listitem>
 132       </varlistentry>
 133       <varlistentry>
 134         <term><option>-m</option></term>
 135         <listitem>
 136           <para>Work with multiple files. This can be used to export
 137             blockdevices that are larger than the maximum allowed
 138             filesize on a given filesystem; i.e. when the filesystem
 139             does not allow files larger than 2GB (which is true for
 140             Linux 2.2 and below), you can use this option to store the
 141             data in multiple files and export a larger filesystem, if
 142             needed.</para>
 143           <para>
 144             To use this option, you must create a number of files
 145             with names in the format "name.X", where "name" is given as
 146             the filename argument to nbd-server, and "X" is a number
 147             starting by 0 and going up for each file.
 148           </para>
 149           <para>
 150             The files must all be 1GB in size.
 151           </para>
 152           <para>
 153             Allowing more flexibility for this option is planned for
 154             future versions.</para>
 155         </listitem>
 156       </varlistentry>
 157       <varlistentry>
 158         <term><option>-c</option></term>
 159         <listitem>
 160           <para>Copy on write. When this option is provided,
 161             write-operations are not done to the exported file, but to a
 162             separate file. This separate file is removed when the
 163             connection is closed, which means that serving this way will
 164             make nbd-server slow down (especially on large block devices
 165             with lots of writes), and that after disconnecting and
 166             reconnecting the client or the server, all changes are
 167             lost.</para>
 168         </listitem>
 169       </varlistentry>
 170       <varlistentry>
 171         <term><option>-C</option></term>
 172         <listitem>
 173           <para>Specify configuration file. The default configuration
 174             file, if this parameter is not specified, is
 175             <filename>@sysconfdir@/nbd-server/config</filename>.</para>
 176           <para>Note that the configuration file is always parsed and
 177             the entries in the file used, even if an extra server is
 178             specified on the command line. To disable the configuration
 179             file entirely, either move it away or use the -C option to
 180             point <command>nbd-server</command>(1) to a non-existing or
 181             empty configuration file.</para>
 182         </listitem>
 183       </varlistentry>
 184       <varlistentry>
 185         <term><option>timeout</option></term>
 186         <listitem>
 187           <para>Maximum number of idle seconds. If a connection is
 188             inactive for this amount of time, it is terminated; this is to
 189             avoid stale nbd-server processes staying in memory. Use of
 190             this option is strongly recommended.</para>
 191         </listitem>
 192       </varlistentry>
 193       <varlistentry>
 194         <term><option>host list</option></term>
 195         <listitem>
 196           <para>This argument should contain a list of IP-addresses
 197             for hosts that may connect to the server. Wildcards are
 198             <emphasis>not</emphasis> allowed. If the file does not
 199             exist, it is ignored (and any host can connect); If the file
 200             does exist, but is empty, no host can connect. By default,
 201             the name 'nbd_server.allow' is used, and looked for in the
 202             current directory, unless nbd-server is compiled as a
 203             daemon, in which case it is looked for in the
 204             root-directory.</para>
 205         </listitem>
 206       </varlistentry>
 207       <varlistentry>
 208         <term><option>section name</option></term>
 209         <listitem>
 210           <para>If the <option>-o</option> argument is given on the
 211           command line, then &dhpackage; will output a configuration
 212           file section with this as the header that is functionally
 213           equivalent to the other options specified on the command line,
 214           and exit. This is useful for migrating pre-2.9 nbd-server
 215           initscript configuration files to the new format.</para>
 216         </listitem>
 217       </varlistentry>
 218     </variablelist>
 219
 220   </refsect1>
 221   <refsect1>
 222     <title>EXAMPLES</title>
 223     <para>Some examples of nbd-server usage:</para>
 224     <itemizedlist mark="none">
 225       <listitem>
 226         <para>To export a file /export/nbd/exp-bl-dev on port 2000:</para>
 227         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev</command></para>
 228       </listitem>
 229       <listitem>
 230         <para>To export a the same file read-only:</para>
 231         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev -r</command></para>
 232       </listitem>
 233       <listitem>
 234         <para>To export the same file read-write, but make sure
 235           changes are lost after restarting the client or the
 236           server:</para>
 237         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev
 238             -c</command></para>
 239       </listitem>
 240     </itemizedlist>
 241   </refsect1>
 242   <refsect1>
 243     <title>SEE ALSO</title>
 244
 245     <para>nbd-client (8), nbd-server (5), http://nbd.sourceforge.net/roadmap.html</para>
 246
 247   </refsect1>
 248   <refsect1>
 249     <title>AUTHOR</title>
 250     <para>The NBD kernel module and the NBD tools were originally
 251       written by Pavel Machek (pavel@ucw.cz)</para>
 252
 253     <para>The Linux kernel module is now maintained by Paul Clements
 254       (Paul.Clements@steeleye.com), while the userland tools are
 255       maintained by &dhusername; (&dhemail;)</para>
 256
 257     <para>On The Hurd there is a regular translator available to perform the
 258       client side of the protocol, and the use of
 259       <command>nbd-client</command> is not required. Please see the
 260       relevant documentation for more information.</para>
 261
 262     <para>This manual page was written by &dhusername; (&dhemail;) for
 263       the &debian; system (but may be used by others).  Permission is
 264       granted to copy, distribute and/or modify this document under
 265       the terms of the <acronym>GNU</acronym> General Public License,
 266       version 2, as published by the Free Software Foundation.</para>
 267
 268   </refsect1>
 269 </refentry>
 270
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