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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>$Date$</date>">
17 <!-- SECTION should be 1-8, maybe w/ subsection other parameters are
18 allowed: see man(7), man(1). -->
19 <!ENTITY dhsection "<manvolnum>8</manvolnum>">
20 <!ENTITY dhemail "<email>wouter@debian.org</email>">
21 <!ENTITY dhusername "Wouter Verhelst">
22 <!ENTITY dhucpackage "<refentrytitle>NBD-CLIENT</refentrytitle>">
23 <!ENTITY dhpackage "nbd-client">
25 <!ENTITY debian "<productname>Debian GNU/Linux</productname>">
26 <!ENTITY gnu "<acronym>GNU</acronym>">
40 <holder>&dhusername;</holder>
50 <refname>&dhpackage;</refname>
52 <refpurpose>connect to a server running nbd-server(1), to use its
53 exported block device</refpurpose>
57 <command>&dhpackage;</command>
58 <arg choice=plain><option><replaceable>host</replaceable></option></arg>
59 <arg choice=plain><option><replaceable>port</replaceable></option></arg>
60 <arg choice=plain><option><replaceable>nbd-device</replaceable></option></arg>
61 <arg><option>-sdp</option></arg>
62 <arg><option>-swap</option></arg>
63 <arg><option>-persist</option></arg>
64 <arg><option>-nofork</option></arg>
65 <arg><option>-block-size <replaceable>block size</replaceable></option></arg>
66 <arg><option>-timeout <replaceable>seconds</replaceable></option></arg>
69 <command>&dhpackage;</command>
70 <arg choice=plain><option>-d <replaceable>nbd-device</replaceable></option></arg>
73 <command>&dhpackage;</command>
74 <arg choice="plain"><option>-c <replaceable>nbd-device</replaceable></option></arg>
78 <title>DESCRIPTION</title>
80 <para>With <command>&dhpackage;</command>, you can connect to a
81 server running <command>nbd-server</command>, thus using raw
82 diskspace from that server as a blockdevice on the local
85 <para>To do this, support from the Linux Kernel is necessary, in
86 the form of the Network Block Device (NBD). When you have that,
87 either in the kernel, or as a module, you can connect to an NBD
88 server and use its exported file through a block special file with
91 <para>Optionally, long options can also be specified with two
92 leading dashes.</para>
95 <title>OPTIONS</title>
97 <para>The following options are supported:</para>
101 <term><option>-block-size <replaceable>block size</replaceable></option></term>
103 <para>Use a blocksize of "block size". Default is 1024;
104 allowed values are either 512, 1024, 2048 or 4096</para>
108 <term><option>host</option></term>
110 <para>The hostname or IP address of the machine running
111 <command>nbd-server</command>. Since 2.9.15, the NBD
112 utilities support IPv6.</para>
116 <term><option>-timeout <replaceable>seconds</replaceable></option></term>
118 <para>Set the connection timeout to "seconds". For this to
119 work, you need a kernel with support for the NBD_SET_TIMEOUT
120 ioctl; this was introduced into Linus' tree on 2007-10-11,
121 and will be part of kernel 2.6.24.</para>
125 <term><option>port</option></term>
127 <para>The TCP port on which <command>nbd-server</command> is
128 running at the server.</para>
132 <term><option>nbd-device</option></term>
134 <para>The block special file this nbd-client should connect
141 <para>Check whether the specified nbd device is
143 <para>If the device is connected, &dhpackage; will exit
144 with an exit state of 0 and print the PID of the &dhpackage;
145 instance that connected it to stdout.
146 <para>If the device is not
147 connected or does not exist (for example because the nbd
148 module was not loaded), &dhpackage; will exit with an exit
149 state of 1 and not print anything on stdout.</para>
150 <para>If an error occurred, &dhpackage; will exit with an exit
151 state of 2, and not print anything on stdout either.</para>
157 <para>Disconnect the specified nbd device from the
162 <term>-persist</term>
164 <para>When this option is specified, &dhpackage; will
165 immediately try to reconnect an nbd device if the
166 connection ever drops unexpectedly due to a lost
167 server or something similar.</para>
171 <term><option>-sdp</option></term>
173 <para>Connect to the server using the Socket Direct Protocol
174 (SDP), rather than IP. See nbd-server(1) for details.
179 <term><option>-swap</option></term>
181 <para>Specifies that this NBD device will be used as
182 swapspace. This option attempts to prevent deadlocks by
183 performing mlockall() at an appropriate time. It does not
184 however guarantee that such deadlocks can be avoided.</para>
188 <term><option>-nofork</option></term>
190 <para>Specifies that the NBD client should not detach and
191 daemonize itself. This is mostly useful for debugging.</para>
196 <title>EXAMPLES</title>
198 <para>Some examples of nbd-client usage:</para>
199 <itemizedlist mark="none">
201 <para>To connect to a server running on port 2000 at host
202 "server.domain.com", using the client's block special file
204 <para><command>nbd-client server.domain.com 2000
205 /dev/nbd0</command></para>
208 <para>To connect to a server running on port 2001 at host
209 "swapserver.domain.com", using the client's block special
210 file "/dev/nb1", for swap purposes:</para>
211 <para><command>nbd-client swapserver.domain.com 2001 /dev/nb1
212 -swap</command></para>
215 <para>To disconnect the above connection again (after making
216 sure the block special file is not in use anymore):</para>
217 <para><command>nbd-client -d /dev/nb1</command></para>
222 <title>SEE ALSO</title>
224 <para>nbd-server (1).</para>
228 <title>AUTHOR</title>
229 <para>The NBD kernel module and the NBD tools have been written by
230 Pavel Macheck (pavel@ucw.cz).</para>
232 <para>The kernel module is now maintained by Paul Clements
233 (Paul.Clements@steeleye.com), while the userland tools are maintained by
234 Wouter Verhelst (wouter@debian.org)</para>
236 <para>This manual page was written by &dhusername; (&dhemail;) for
237 the &debian; system (but may be used by others). Permission is
238 granted to copy, distribute and/or modify this document under the
239 terms of the <acronym>GNU</acronym> General Public License,
240 version 2, as published by the Free Software Foundation.</para>
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