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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
93 <title>OPTIONS</title>
95 <para>The following options are supported:</para>
99 <term><option>-block-size <replaceable>block size</replaceable></option></term>
101 <para>Use a blocksize of "block size". Default is 1024;
102 allowed values are either 512, 1024, 2048 or 4096</para>
106 <term><option>host</option></term>
108 <para>The hostname or IP address of the machine running
109 <command>nbd-server</command>. Since 2.9.15, the NBD
110 utilities support IPv6.</para>
114 <term><option>-timeout <replaceable>seconds</replaceable></option></term>
116 <para>Set the connection timeout to "seconds". For this to
117 work, you need a kernel with support for the NBD_SET_TIMEOUT
118 ioctl; this was introduced into Linus' tree on 2007-10-11,
119 and will be part of kernel 2.6.24.</para>
123 <term><option>port</option></term>
125 <para>The TCP port on which <command>nbd-server</command> is
126 running at the server.</para>
130 <term><option>nbd-device</option></term>
132 <para>The block special file this nbd-client should connect
139 <para>Check whether the specified nbd device is
141 <para>If the device is connected, &dhpackage; will exit
142 with an exit state of 0 and print the PID of the &dhpackage;
143 instance that connected it to stdout.
144 <para>If the device is not
145 connected or does not exist (for example because the nbd
146 module was not loaded), &dhpackage; will exit with an exit
147 state of 1 and not print anything on stdout.</para>
148 <para>If an error occurred, &dhpackage; will exit with an exit
149 state of 2, and not print anything on stdout either.</para>
155 <para>Disconnect the specified nbd device from the
160 <term>-persist</term>
162 <para>When this option is specified, &dhpackage; will
163 immediately try to reconnect an nbd device if the
164 connection ever drops unexpectedly due to a lost
165 server or something similar.</para>
169 <term><option>-sdp</option></term>
171 <para>Connect to the server using the Socket Direct Protocol
172 (SDP), rather than IP. See nbd-server(1) for details.
177 <term><option>-swap</option></term>
179 <para>Specifies that this NBD device will be used as
180 swapspace. This option attempts to prevent deadlocks by
181 performing mlockall() at an appropriate time. It does not
182 however guarantee that such deadlocks can be avoided.</para>
186 <term><option>-nofork</option></term>
188 <para>Specifies that the NBD client should not detach and
189 daemonize itself. This is mostly useful for debugging.</para>
194 <title>EXAMPLES</title>
196 <para>Some examples of nbd-client usage:</para>
197 <itemizedlist mark="none">
199 <para>To connect to a server running on port 2000 at host
200 "server.domain.com", using the client's block special file
202 <para><command>nbd-client server.domain.com 2000
203 /dev/nbd0</command></para>
206 <para>To connect to a server running on port 2001 at host
207 "swapserver.domain.com", using the client's block special
208 file "/dev/nb1", for swap purposes:</para>
209 <para><command>nbd-client swapserver.domain.com 2001 /dev/nb1
210 -swap</command></para>
213 <para>To disconnect the above connection again (after making
214 sure the block special file is not in use anymore):</para>
215 <para><command>nbd-client -d /dev/nb1</command></para>
220 <title>SEE ALSO</title>
222 <para>nbd-server (1).</para>
226 <title>AUTHOR</title>
227 <para>The NBD kernel module and the NBD tools have been written by
228 Pavel Macheck (pavel@ucw.cz).</para>
230 <para>The kernel module is now maintained by Paul Clements
231 (Paul.Clements@steeleye.com), while the userland tools are maintained by
232 Wouter Verhelst (wouter@debian.org)</para>
234 <para>This manual page was written by &dhusername; (&dhemail;) for
235 the &debian; system (but may be used by others). Permission is
236 granted to copy, distribute and/or modify this document under the
237 terms of the <acronym>GNU</acronym> General Public License,
238 version 2, as published by the Free Software Foundation.</para>
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