nbd-server.1.sgml

   1 <!doctype refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN" [
   2
   3 <!-- Process this file with docbook-to-man to generate an nroff manual
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   6      less'.  A typical entry in a Makefile or Makefile.am is:
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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>$Date$</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     </cmdsynopsis>
  69   </refsynopsisdiv>
  70   <refsect1>
  71     <title>DESCRIPTION</title>
  72
  73     <para>This manual page documents the
  74       <command>&dhpackage;</command> command.</para>
  75
  76     <para>This manual page was written for the &debian; distribution
  77       because the original program does not have a manual page.</para>
  78
  79     <para><command>&dhpackage;</command> is the server for the Linux
  80     Network Block Device (NBD). With NBD, a client can use a file,
  81     exported over the network from a server, as a block device. It can
  82     then be used for whatever purpose a normal block device (harddisk,
  83     CD-ROM, ...) can be used for.</para>
  84
  85     <para>NBD can be useful for diskless clients that need swapspace,
  86     but you can also create a filesystem on it and use it as though it
  87     were a local filesystem.</para>
  88
  89     <para><command>&dhpackage;</command> implements some security
  90     through a file called "nbd_server.allow" in the current directory (by default; a different file can be chosen with the '-l' option).
  91     This file must list the IP-addresses of clients that are allowed
  92     to connect. If it does not exist, all clients are able to connect.
  93     If the file is empty, no clients can connect.</para>
  94   </refsect1>
  95   <refsect1>
  96     <title>OPTIONS</title>
  97
  98     <variablelist>
  99       <varlistentry>
 100         <term><option>port</option>
 101         </term>
 102         <listitem>
 103           <para>The port the server should listen to. A valid port is
 104             any number between 1 and 65536; if 0 is used, nbd-server
 105             will listen on stdin (so that nbd-server can be ran from
 106             inetd)</para>
 107         </listitem>
 108       </varlistentry>
 109       <varlistentry>
 110         <term><option>filename</option></term>
 111         <listitem>
 112           <para>The filename of the file that should be exported. This
 113           can be any file, including "real" blockdevices (i.e. a file
 114           from /dev). If the filename includes the literal string
 115           "%s", then this %s will be substituded with the IP-address
 116           of the client trying to connect.</para>
 117         </listitem>
 118       </varlistentry>
 119       <varlistentry>
 120         <term><option>size</option></term>
 121         <listitem>
 122           <para>The size of the block device at the client side. This
 123             is especially usefull in conjunction with the -m
 124             option</para>
 125           <para>Can optionally be followed by one of K,k,M or
 126             m, in which case the size will be multiplied by 1024 (K
 127             or k) or 1048576 (M or m)</para>
 128         </listitem>
 129       </varlistentry>
 130       <varlistentry>
 131         <term><option>-r</option></term>
 132         <listitem>
 133           <para>Export the file read-only. If a client tries to write
 134             to a read-only exported file, it will receive an error, but
 135             the connection will stay up.</para>
 136         </listitem>
 137       </varlistentry>
 138       <varlistentry>
 139         <term><option>-m</option></term>
 140         <listitem>
 141           <para>Work with multiple files. This can be used to export
 142             blockdevices that are larger than the maximum allowed
 143             filesize on a given filesystem; i.e. when the filesystem
 144             does not allow files larger than 2GB (which is true for
 145             Linux 2.2 and below), you can use this option to store the
 146             data in multiple files and export a larger filesystem, if
 147             needed.</para>
 148           <para>
 149             To use this option, you must create a number of files
 150             with names in the format "name.X", where "name" is given as
 151             the filename argument to nbd-server, and "X" is a number
 152             starting by 0 and going up for each file.
 153           </para>
 154           <para>
 155             The files must all be 1GB in size.
 156           </para>
 157           <para>
 158             Allowing more flexibility for this option is planned for
 159             future versions.</para>
 160         </listitem>
 161       </varlistentry>
 162       <varlistentry>
 163         <term><option>-c</option></term>
 164         <listitem>
 165           <para>Copy on write. When this option is provided,
 166           write-operations are not done to the exported file, but to a
 167           separate file. This separate file is removed when the
 168           connection is closed, which means that serving this way will
 169           make nbd-server slow down (especially on large block devices
 170           with lots of writes), and that after disconnecting and
 171           reconnecting the client or the server, all changes are
 172           lost.</para>
 173         </listitem>
 174       </varlistentry>
 175       <varlistentry>
 176         <term><option>timeout</option></term>
 177         <listitem>
 178           <para>Maximum number of idle seconds. If a connection is
 179           inactive for this amount of time, it is terminated; this is to
 180           avoid stale nbd-server processes staying in memory. Use of
 181           this option is strongly recommended.</para>
 182         </listitem>
 183       </varlistentry>
 184       <varlistentry>
 185         <term><option>host list</option></term>
 186         <listitem>
 187           <para>This argument should contain a list of IP-addresses
 188           for hosts that may connect to the server. Wildcards are
 189           <emphasis>not</emphasis> allowed. If the file does not
 190           exist, it is ignored (and any host can connect); If the file
 191           does exist, but is empty, no host can connect. By default,
 192           the name 'nbd_server.allow' is used, and looked for in the
 193           current directory, unless nbd-server is compiled as a
 194           daemon, in which case it is looked for in the
 195           root-directory.</para>
 196         </listitem>
 197       </varlistentry>
 198     </variablelist>
 199
 200   </refsect1>
 201   <refsect1>
 202     <title>EXAMPLES</title>
 203     <para>Some examples of nbd-server usage:</para>
 204     <itemizedlist mark="none">
 205       <listitem>
 206         <para>To export a file /export/nbd/exp-bl-dev on port 2000:</para>
 207         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev</command></para>
 208       </listitem>
 209       <listitem>
 210         <para>To export a the same file read-only:</para>
 211         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev -r</command></para>
 212       </listitem>
 213       <listitem>
 214         <para>To export the same file read-write, but make sure
 215           changes are lost after restarting the client or the
 216           server:</para>
 217         <para><command>nbd-server 2000 /export/nbd/exp-bl-dev
 218           -c</command></para>
 219       </listitem>
 220     </itemizedlist>
 221   </refsect1>
 222   <refsect1>
 223     <title>SEE ALSO</title>
 224
 225     <para>nbd-client (8), http://nbd.sourceforge.net/roadmap.html</para>
 226
 227   </refsect1>
 228   <refsect1>
 229     <title>AUTHOR</title>
 230     <para>The NBD kernel module and the NBD tools were originally
 231       written by Pavel Machek (pavel@ucw.cz)</para>
 232
 233     <para>The kernel module is now maintained by Paul Clements
 234       (Paul.Clements@steeleye.com), while the userland tools are
 235       maintained by &dhusername; (&dhemail;)</para>
 236
 237     <para>This manual page was written by &dhusername; (&dhemail;) for
 238       the &debian; system (but may be used by others).  Permission is
 239       granted to copy, distribute and/or modify this document under
 240       the terms of the <acronym>GNU</acronym> General Public License,
 241       version 2, as published by the Free Software Foundation.</para>
 242
 243   </refsect1>
 244 </refentry>
 245
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