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<?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
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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
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You should have received a copy of the GNU Lesser General Public License
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-->
<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>Discard=</varname></term>
<listitem><para>Enable discards, if the swap
backing device supports the discard or trim
operation. Can be one of <literal>none</literal>,
<literal>once</literal>, <literal>pages</literal>
or <literal>all</literal>. Defaults to
<literal>none</literal>. (See
<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for more information.)
</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 <literal>0</literal> to disable the timeout
logic. Defaults to <varname>DefaultTimeoutStartSec=</varname> from the
manager configuration file
(see <citerefentry><refentrytitle>systemd-systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</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>1</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>
|
