<?xml version='1.0'?> <!--*-nxml-*--> <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2010 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <refentry id="systemd.swap"> <refentryinfo> <title>systemd.swap</title> <productname>systemd</productname> <authorgroup> <author> <contrib>Developer</contrib> <firstname>Lennart</firstname> <surname>Poettering</surname> <email>lennart@poettering.net</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>systemd.swap</refentrytitle> <manvolnum>5</manvolnum> </refmeta> <refnamediv> <refname>systemd.swap</refname> <refpurpose>Swap unit configuration</refpurpose> </refnamediv> <refsynopsisdiv> <para><filename><replaceable>swap</replaceable>.swap</filename></para> </refsynopsisdiv> <refsect1> <title>Description</title> <para>A unit configuration file whose name ends in <literal>.swap</literal> encodes information about a swap device or file for memory paging controlled and supervised by systemd.</para> <para>This man page lists the configuration options specific to this unit type. See <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for the common options of all unit configuration files. The common configuration items are configured in the generic [Unit] and [Install] sections. The swap specific configuration options are configured in the [Swap] section.</para> <para>Additional options are listed in <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, which define the execution environment the <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry> binary is executed in, and in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, which define the way the processes are terminated, and in <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, which configure resource control settings for the processes of the service.</para> <para>Swap units must be named after the devices or files they control. Example: the swap device <filename noindex='true'>/dev/sda5</filename> must be configured in a unit file <filename>dev-sda5.swap</filename>. For details about the escaping logic used to convert a file system path to a unit name see <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> <para>All swap units automatically get the appropriate dependencies on the devices or on the mount points of the files they are activated from.</para> <para>Swap units with <varname>DefaultDependencies=</varname> enabled implicitly acquire a conflicting dependency to <filename>umount.target</filename> so that they are deactivated at shutdown.</para> </refsect1> <refsect1> <title><filename>fstab</filename></title> <para>Swap units may either be configured via unit files, or via <filename>/etc/fstab</filename> (see <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details). Swaps listed in <filename>/etc/fstab</filename> will be converted into native units dynamically at boot and when the configuration of the system manager is reloaded. See <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> for details about the conversion.</para> <para>If a swap device or file is configured in both <filename>/etc/fstab</filename> and a unit file, the configuration in the latter takes precedence.</para> <para>Unless the <option>noauto</option> option is set for them all swap units configured in <filename>/etc/fstab</filename> are also added as requirements to <filename>swap.target</filename>, so that they are waited for and activated during boot.</para> </refsect1> <refsect1> <title>Options</title> <para>Swap files must include a [Swap] section, which carries information about the swap device it supervises. A number of options that may be used in this section are shared with other unit types. These options are documented in <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> and <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The options specific to the [Swap] section of swap units are the following:</para> <variablelist class='unit-directives'> <varlistentry> <term><varname>What=</varname></term> <listitem><para>Takes an absolute path of a device node or file to use for paging. See <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry> for details. If this refers to a device node, a dependency on the respective device unit is automatically created. (See <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.) If this refers to a file, a dependency on the respective mount unit is automatically created. (See <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.) This option is mandatory.</para></listitem> </varlistentry> <varlistentry> <term><varname>Priority=</varname></term> <listitem><para>Swap priority to use when activating the swap device or file. This takes an integer. This setting is optional.</para></listitem> </varlistentry> <varlistentry> <term><varname>TimeoutSec=</varname></term> <listitem><para>Configures the time to wait for the swapon command to finish. If a command does not exit within the configured time, the swap will be considered failed and be shut down again. All commands still running will be terminated forcibly via <constant>SIGTERM</constant>, and after another delay of this time with <constant>SIGKILL</constant>. (See <option>KillMode=</option> in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.) Takes a unit-less value in seconds, or a time span value such as "5min 20s". Pass 0 to disable the timeout logic. Defaults to <varname>TimeoutStartSec=</varname> from the manager configuration file.</para></listitem> </varlistentry> </variablelist> <para>Check <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> and <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more settings.</para> </refsect1> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry> </para> </refsect1> </refentry>