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e0cabd4b | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
e0cabd4b | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
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11 | under the terms of the GNU Lesser General Public License as published by |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
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13 | (at your option) any later version. |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 18 | Lesser General Public License for more details. |
e0cabd4b | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd.swap"> | |
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25 | <refentryinfo> |
26 | <title>systemd.swap</title> | |
27 | <productname>systemd</productname> | |
28 | ||
29 | <authorgroup> | |
30 | <author> | |
31 | <contrib>Developer</contrib> | |
32 | <firstname>Lennart</firstname> | |
33 | <surname>Poettering</surname> | |
34 | <email>lennart@poettering.net</email> | |
35 | </author> | |
36 | </authorgroup> | |
37 | </refentryinfo> | |
38 | ||
39 | <refmeta> | |
40 | <refentrytitle>systemd.swap</refentrytitle> | |
41 | <manvolnum>5</manvolnum> | |
42 | </refmeta> | |
43 | ||
44 | <refnamediv> | |
45 | <refname>systemd.swap</refname> | |
46 | <refpurpose>Swap unit configuration</refpurpose> | |
47 | </refnamediv> | |
48 | ||
49 | <refsynopsisdiv> | |
50 | <para><filename><replaceable>swap</replaceable>.swap</filename></para> | |
51 | </refsynopsisdiv> | |
52 | ||
53 | <refsect1> | |
54 | <title>Description</title> | |
55 | ||
56 | <para>A unit configuration file whose name ends in | |
57 | <literal>.swap</literal> encodes information about a swap device | |
58 | or file for memory paging controlled and supervised by | |
59 | systemd.</para> | |
60 | ||
61 | <para>This man page lists the configuration options specific to | |
62 | this unit type. See | |
63 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
64 | for the common options of all unit configuration files. The common | |
65 | configuration items are configured in the generic [Unit] and | |
66 | [Install] sections. The swap specific configuration options are | |
67 | configured in the [Swap] section.</para> | |
68 | ||
69 | <para>Additional options are listed in | |
70 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
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71 | which define the execution environment the <citerefentry |
72 | project='man-pages'><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
73 | binary is executed in, in | |
798d3a52 | 74 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
c629ff58 | 75 | which define the way these processes are |
c129bd5d | 76 | terminated, and in |
798d3a52 | 77 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
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78 | which configure resource control settings for these processes of the |
79 | unit.</para> | |
798d3a52 | 80 | |
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81 | <para>Swap units must be named after the devices or files they control. Example: the swap device <filename |
82 | noindex='true'>/dev/sda5</filename> must be configured in a unit file <filename>dev-sda5.swap</filename>. For | |
83 | details about the escaping logic used to convert a file system path to a unit name, see | |
84 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Note that swap | |
85 | units cannot be templated, nor is possible to add multiple names to a swap unit by creating additional symlinks to | |
86 | it.</para> | |
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87 | </refsect1> |
88 | ||
89 | <refsect1> | |
45f09f93 | 90 | <title>Implicit Dependencies</title> |
798d3a52 | 91 | |
45f09f93 | 92 | <para>The following dependencies are implicitly added:</para> |
798d3a52 | 93 | |
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94 | <itemizedlist> |
95 | <listitem><para>All swap units automatically get the | |
96 | <varname>BindsTo=</varname> and <varname>After=</varname> | |
97 | dependencies on the device units or the mount units of the files | |
98 | they are activated from.</para></listitem> | |
99 | </itemizedlist> | |
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100 | |
101 | <para>Additional implicit dependencies may be added as result of | |
102 | execution and resource control parameters as documented in | |
103 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
104 | and | |
105 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> | |
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106 | </refsect1> |
107 | ||
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108 | <refsect1> |
109 | <title>Default Dependencies</title> | |
110 | ||
111 | <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para> | |
112 | ||
113 | <itemizedlist> | |
114 | <listitem><para>Swap units automatically acquire a <varname>Conflicts=</varname> and a | |
115 | <varname>Before=</varname> dependency on <filename>umount.target</filename> so that they are deactivated at | |
116 | shutdown as well as a <varname>Before=swap.target</varname> dependency.</para></listitem> | |
117 | </itemizedlist> | |
118 | </refsect1> | |
119 | ||
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120 | <refsect1> |
121 | <title><filename>fstab</filename></title> | |
122 | ||
123 | <para>Swap units may either be configured via unit files, or via | |
124 | <filename>/etc/fstab</filename> (see | |
3ba3a79d | 125 | <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
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126 | for details). Swaps listed in <filename>/etc/fstab</filename> will |
127 | be converted into native units dynamically at boot and when the | |
128 | configuration of the system manager is reloaded. See | |
129 | <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
130 | for details about the conversion.</para> | |
131 | ||
132 | <para>If a swap device or file is configured in both | |
133 | <filename>/etc/fstab</filename> and a unit file, the configuration | |
134 | in the latter takes precedence.</para> | |
135 | ||
b938cb90 | 136 | <para>When reading <filename>/etc/fstab</filename>, a few special |
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137 | options are understood by systemd which influence how dependencies |
138 | are created for swap units.</para> | |
139 | ||
140 | <variablelist class='fstab-options'> | |
141 | <varlistentry> | |
142 | <term><option>noauto</option></term> | |
143 | <term><option>auto</option></term> | |
144 | ||
b938cb90 | 145 | <listitem><para>With <option>noauto</option>, the swap unit |
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146 | will not be added as a dependency for |
147 | <filename>swap.target</filename>. This means that it will not | |
148 | be activated automatically during boot, unless it is pulled in | |
a8eaaee7 | 149 | by some other unit. The <option>auto</option> option has the |
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150 | opposite meaning and is the default.</para> |
151 | </listitem> | |
152 | </varlistentry> | |
153 | ||
154 | <varlistentry> | |
155 | <term><option>nofail</option></term> | |
156 | ||
b938cb90 | 157 | <listitem><para>With <option>nofail</option>, the swap unit |
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158 | will be only wanted, not required by |
159 | <filename>swap.target</filename>. This means that the boot | |
160 | will continue even if this swap device is not activated | |
161 | successfully.</para> | |
162 | </listitem> | |
163 | </varlistentry> | |
164 | </variablelist> | |
165 | </refsect1> | |
166 | ||
167 | <refsect1> | |
168 | <title>Options</title> | |
169 | ||
170 | <para>Swap files must include a [Swap] section, which carries | |
171 | information about the swap device it supervises. A number of | |
172 | options that may be used in this section are shared with other | |
173 | unit types. These options are documented in | |
174 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
175 | and | |
176 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
177 | The options specific to the [Swap] section of swap units are the | |
178 | following:</para> | |
179 | ||
180 | <variablelist class='unit-directives'> | |
181 | ||
182 | <varlistentry> | |
183 | <term><varname>What=</varname></term> | |
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184 | <listitem><para>Takes an absolute path of a device node or file to use for paging. See <citerefentry |
185 | project='man-pages'><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry> for | |
186 | details. If this refers to a device node, a dependency on the respective device unit is automatically | |
187 | created. (See | |
188 | <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more | |
189 | information.) If this refers to a file, a dependency on the respective mount unit is automatically | |
190 | created. (See <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
191 | for more information.) This option is mandatory. Note that the usual specifier expansion is applied to this | |
192 | setting, literal percent characters should hence be written as <literal>%%</literal>.</para></listitem> | |
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193 | </varlistentry> |
194 | ||
195 | <varlistentry> | |
196 | <term><varname>Priority=</varname></term> | |
197 | ||
198 | <listitem><para>Swap priority to use when activating the swap | |
199 | device or file. This takes an integer. This setting is | |
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200 | optional and ignored when the priority is set by <option>pri=</option> in the |
201 | <varname>Options=</varname> key.</para></listitem> | |
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202 | </varlistentry> |
203 | ||
204 | <varlistentry> | |
205 | <term><varname>Options=</varname></term> | |
206 | ||
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207 | <listitem><para>May contain an option string for the swap device. This may be used for controlling discard |
208 | options among other functionality, if the swap backing device supports the discard or trim operation. (See | |
3ba3a79d | 209 | <citerefentry project='man-pages'><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
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210 | for more information.) Note that the usual specifier expansion is applied to this setting, literal percent |
211 | characters should hence be written as <literal>%%</literal>.</para></listitem> | |
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212 | </varlistentry> |
213 | ||
214 | <varlistentry> | |
215 | <term><varname>TimeoutSec=</varname></term> | |
216 | <listitem><para>Configures the time to wait for the swapon | |
217 | command to finish. If a command does not exit within the | |
218 | configured time, the swap will be considered failed and be | |
219 | shut down again. All commands still running will be terminated | |
220 | forcibly via <constant>SIGTERM</constant>, and after another | |
221 | delay of this time with <constant>SIGKILL</constant>. (See | |
222 | <option>KillMode=</option> in | |
223 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.) | |
224 | Takes a unit-less value in seconds, or a time span value such | |
225 | as "5min 20s". Pass <literal>0</literal> to disable the | |
226 | timeout logic. Defaults to | |
227 | <varname>DefaultTimeoutStartSec=</varname> from the manager | |
228 | configuration file (see | |
229 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
230 | </para></listitem> | |
231 | </varlistentry> | |
232 | </variablelist> | |
233 | ||
234 | <para>Check | |
235 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
236 | and | |
237 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
238 | for more settings.</para> | |
239 | </refsect1> | |
240 | ||
241 | <refsect1> | |
242 | <title>See Also</title> | |
243 | <para> | |
244 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
245 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
246 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
247 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
248 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
249 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
250 | <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
251 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
3ba3a79d | 252 | <citerefentry project='man-pages'><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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253 | <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
254 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
255 | </para> | |
256 | </refsect1> | |
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257 | |
258 | </refentry> |