man/systemd.swap.xml

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  24
  25 <refentry id="systemd.swap">
  26         <refentryinfo>
  27                 <title>systemd.swap</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemd.swap</refentrytitle>
  42                 <manvolnum>5</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.swap</refname>
  47                 <refpurpose>systemd swap configuration files</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename>systemd.swap</filename></para>
  52         </refsynopsisdiv>
  53
  54         <refsect1>
  55                 <title>Description</title>
  56
  57                 <para>A unit configuration file whose name ends in
  58                 <filename>.swap</filename> encodes information about a
  59                 swap device or file for memory paging controlled and
  60                 supervised by systemd.</para>
  61
  62                 <para>This man page lists the configuration options
  63                 specific to this unit type. See
  64                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  65                 for the common options of all unit configuration
  66                 files. The common configuration items are configured
  67                 in the generic [Unit] and [Install] sections. The swap
  68                 specific configuration options are configured in the
  69                 [Swap] section.</para>
  70
  71                 <para>Swap units must be named after the devices
  72                 (resp. files) they control. Example: the swap device
  73                 <filename>/dev/sda5</filename> must be configured in a
  74                 unit file <filename>dev-sda5.swap</filename>. For
  75                 details about the escaping logic used to convert a
  76                 file system path to a unit name see
  77                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  78
  79                 <para>All swap units automatically get the appropriate
  80                 dependencies on the devices (resp. on the mount points
  81                 of the files) they are activated from.</para>
  82
  83                 <para>Swap units with
  84                 <varname>DefaultDependencies=</varname> enabled
  85                 implicitly acquire a conflicting dependency to
  86                 <filename>umount.target</filename> so that they are
  87                 deactivated at shutdown.</para>
  88         </refsect1>
  89
  90         <refsect1>
  91                 <title><filename>fstab</filename></title>
  92
  93                 <para>Swap units may either be configured via unit
  94                 files, or via <filename>/etc/fstab</filename> (see
  95                 <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  96                 for details).</para>
  97
  98                 <para>If a swap device or file is configured in both
  99                 <filename>/etc/fstab</filename> and a unit file the
 100                 configuration in the latter takes precedence.</para>
 101
 102                 <para>Unless the <option>noauto</option> option is set
 103                 for them all swap units configured in
 104                 <filename>/etc/fstab</filename> are also added as
 105                 requirements to <filename>swap.target</filename>, so
 106                 that they are waited for and activated during
 107                 boot.</para>
 108         </refsect1>
 109
 110         <refsect1>
 111                 <title>Options</title>
 112
 113                 <para>Swap files must include a [Swap] section, which
 114                 carries information about the swap device it
 115                 supervises. A number of options that may be used in
 116                 this section are shared with other unit types. These
 117                 options are documented in
 118                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
 119                 options specific to the [Swap] section of swap units
 120                 are the following:</para>
 121
 122                 <variablelist>
 123
 124                         <varlistentry>
 125                                 <term><varname>What=</varname></term>
 126                                 <listitem><para>Takes an absolute path
 127                                 of a device node or file to use for
 128                                 paging. See
 129                                 <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 130                                 for details. If this refers to a
 131                                 device node, a dependency on the
 132                                 respective device unit is
 133                                 automatically created. (See
 134                                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 135                                 for more information.) If this refers
 136                                 to a file, a dependency on the
 137                                 respective mount unit is automatically
 138                                 created. (See
 139                                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 140                                 for more information.) This option is
 141                                 mandatory.</para></listitem>
 142                         </varlistentry>
 143
 144                         <varlistentry>
 145                                 <term><varname>Priority=</varname></term>
 146
 147                                 <listitem><para>Swap priority to use
 148                                 when activating the swap device or
 149                                 file. This takes an integer. This
 150                                 setting is optional.</para></listitem>
 151                         </varlistentry>
 152
 153                         <varlistentry>
 154                                 <term><varname>TimeoutSec=</varname></term>
 155                                 <listitem><para>Configures the time to
 156                                 wait for the swapon command to
 157                                 finish. If a command does not exit
 158                                 within the configured time the swap
 159                                 will be considered failed and be shut
 160                                 down again. All commands still running
 161                                 will be terminated forcibly via
 162                                 SIGTERM, and after another delay of
 163                                 this time with SIGKILL. (See
 164                                 <option>KillMode=</option> below.)
 165                                 Takes a unit-less value in seconds, or
 166                                 a time span value such as "5min
 167                                 20s". Pass 0 to disable the timeout
 168                                 logic. Defaults to
 169                                 90s.</para></listitem>
 170                         </varlistentry>
 171
 172                         <varlistentry>
 173                                 <term><varname>KillMode=</varname></term>
 174                                 <listitem><para>Specifies how
 175                                 processes of this swap shall be
 176                                 killed. One of
 177                                 <option>control-group</option>,
 178                                 <option>process</option>,
 179                                 <option>none</option>.</para>
 180
 181                                 <para>This option is mostly equivalent
 182                                 to the <option>KillMode=</option>
 183                                 option of service files. See
 184                                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 185                                 for details.</para></listitem>
 186                         </varlistentry>
 187
 188                         <varlistentry>
 189                                 <term><varname>KillSignal=</varname></term>
 190                                 <listitem><para>Specifies which signal
 191                                 to use when killing a process of this
 192                                 swap. Defaults to SIGTERM.
 193                                 </para></listitem>
 194                         </varlistentry>
 195
 196                         <varlistentry>
 197                                 <term><varname>SendSIGKILL=</varname></term>
 198                                 <listitem><para>Specifies whether to
 199                                 send SIGKILL to remaining processes
 200                                 after a timeout, if the normal
 201                                 shutdown procedure left processes of
 202                                 the swap around. Takes a boolean
 203                                 value. Defaults to "yes".
 204                                 </para></listitem>
 205                         </varlistentry>
 206                 </variablelist>
 207         </refsect1>
 208
 209         <refsect1>
 210                   <title>See Also</title>
 211                   <para>
 212                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 213                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 214                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 215                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 216                           <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 217                           <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 218                           <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 219                   </para>
 220         </refsect1>
 221
 222 </refentry>