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8 manpage.1: manpage.sgml
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>september 19, 2001</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">
25 <!ENTITY debian "<productname>Debian GNU/Linux</productname>">
26 <!ENTITY gnu "<acronym>GNU</acronym>">
40 <holder>&dhusername;</holder>
50 <refname>&dhpackage;</refname>
52 <refpurpose>serve a file as a block device to other computers
53 running the &gnu;/Linux(tm) or &gnu;/Hurd Operating
58 <command>&dhpackage;</command>
60 <arg><option>-c <replaceable>this</replaceable></option></arg>
61 <arg choice=plain><replaceable>port</replaceable</arg>
62 <arg choice=plain><replaceable>filename</replaceable></arg>
63 <arg><replaceable>size</replaceable></arg>
64 <arg><option>-r</option></arg>
65 <arg><option>-m</option></arg>
66 <arg><option>-c</option></arg>
70 <title>DESCRIPTION</title>
72 <para>This manual page documents the
73 <command>&dhpackage;</command> command.</para>
75 <para>This manual page was written for the &debian; distribution
76 because the original program does not have a manual page.</para>
78 <para><command>&dhpackage;</command> is the server for the Linux
79 Network Block Device (NBD). With NBD, a client can use a file,
80 exported over the network from a server, as a block device. It can
81 then be used for whatever purpose a normal block device (harddisk,
82 CD-ROM, ...) can be used for.</para>
84 <para>NBD can be usefull for diskless clients that need swapspace,
85 but you can also create a filesystem on it and use it as though it
86 were a local filesystem.</para>
88 <para><command>&dhpackage;</command> implements some security
89 through a file called "nbd_server.allow" in the current directory.
90 This file must list the IP-addresses of clients that are allowed
91 to connect. If it does not exist, all clients are able to connect.
92 If the file is empty, no clients can connect.</para>
95 <title>OPTIONS</title>
99 <term><option>port</option>
102 <para>The port the server should listen to. A valid port is
103 any number between 1 and 65536; if 0 is used, nbd-server
104 will listen on stdin (so that nbd-server can be ran from
109 <term><option>filename</option></term>
111 <para>The filename of the file that should be exported. This
112 can be any file, including "real" blockdevices (i.e. a file
113 from /dev). If the filename includes the literal string
114 "%s", then this %s will be substituded with the IP-address
115 of the client trying to connect.</para>
119 <term><option>size</option></term>
121 <para>The size of the block device at the client side. This
122 is especially usefull in conjunction with the -m
124 <para>Can optionally be followed by one of K,k,M or
125 m, in which case the size will be multiplied by 1024 (K
126 or k) or 1048576 (M or m)</para>
130 <term><option>-r</option></term>
132 <para>Export the file read-only. If a client tries to write
133 to a read-only exported file, it will receive an error, but
134 the connection will stay up.</para>
138 <term><option>-m</option></term>
140 <para>Work with multiple files. This can be used to export
141 blockdevices that are larger than the maximum allowed
142 filesize on a given filesystem; i.e. when the filesystem
143 does not allow files larger than 2GB (which is true for
144 Linux 2.2 and below), you can use this option to store the
145 data in multiple files and export a larger filesystem, if
150 <term><option>-c</option></term>
152 <para>Copy on write. When this option is provided,
153 write-operations are not done to the exported file, but to a
154 separate file. This separate file is removed when the
155 connection is closed, which means that serving this way will
156 make nbd-server slow down (especially on large block devices
157 with lots of writes), and that after disconnecting and
158 reconnecting the client or the server, all changes are
165 <title>EXAMPLES</title>
166 <para>Some examples of nbd-server usage:</para>
167 <itemizedlist mark="none">
169 <para>To export a file /export/nbd/exp-bl-dev on port 2000:</para>
170 <para><command>nbd-server 2000 /export/nbd/exp-bl-dev</command></para>
173 <para>To export a the same file read-only:</para>
174 <para><command>nbd-server 2000 /export/nbd/exp-bl-dev -r</command></para>
177 <para>To export the same file read-write, but make sure
178 changes are lost after restarting the client or the
180 <para><command>nbd-server 2000 /export/nbd/exp-bl-dev
190 <term><filename>nbd_server.allow</filename></term>
192 <para>This file, which must be in the directory where
193 nbd-server is invoked, can contain a list of IP-addresses
194 for hosts that may connect to the server. Wildcards are
202 <title>SEE ALSO</title>
204 <para>nbd-client (8).</para>
208 <title>AUTHOR</title>
209 <para>The NBD kernel module and the NBD tools were written by
210 Pavel Machek (pavel@ucw.cz)</para>
212 <para>This manual page was written by &dhusername; (&dhemail;) for
213 the &debian; system (but may be used by others). Permission is
214 granted to copy, distribute and/or modify this document under
215 the terms of the <acronym>GNU</acronym> Free Documentation
216 License, Version 1.1 or any later version published by the Free
217 Software Foundation; with no Invariant Sections, no Front-Cover
218 Texts and no Back-Cover Texts.</para>
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