man/systemd.swap.xml

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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>systemd swap configuration files</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <para><filename>systemd.swap</filename></para>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para>A unit configuration file whose name ends in
                <filename>.swap</filename> 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>Swap units must be named after the devices they
                control. Example: the swap device
                <filename>/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>
        </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).</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>
        </refsect1>

        <refsect1>
                <title>Options</title>

                <para>Swap files must include a [Swap] section, which
                carries information about the swap device it
                supervises. The options specific to the [Swap] section
                of swap units are the following:</para>

                <variablelist>

                        <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>
                </variablelist>
        </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.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                          <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                          <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                  </para>
        </refsect1>

</refentry>