man/systemd.swap.xml

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   9   Copyright 2010 Lennart Poettering
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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). Swaps listed in
  97                 <filename>/etc/fstab</filename> will be converted into
  98                 native units dynamically at boot and when the
  99                 configuration of the system manager is
 100                 reloaded. See
 101                 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 102                 for details about the conversion.</para>
 103
 104                 <para>If a swap device or file is configured in both
 105                 <filename>/etc/fstab</filename> and a unit file the
 106                 configuration in the latter takes precedence.</para>
 107
 108                 <para>Unless the <option>noauto</option> option is set
 109                 for them all swap units configured in
 110                 <filename>/etc/fstab</filename> are also added as
 111                 requirements to <filename>swap.target</filename>, so
 112                 that they are waited for and activated during
 113                 boot.</para>
 114         </refsect1>
 115
 116         <refsect1>
 117                 <title>Options</title>
 118
 119                 <para>Swap files must include a [Swap] section, which
 120                 carries information about the swap device it
 121                 supervises. A number of options that may be used in
 122                 this section are shared with other unit types. These
 123                 options are documented in
 124                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
 125                 options specific to the [Swap] section of swap units
 126                 are the following:</para>
 127
 128                 <variablelist>
 129
 130                         <varlistentry>
 131                                 <term><varname>What=</varname></term>
 132                                 <listitem><para>Takes an absolute path
 133                                 of a device node or file to use for
 134                                 paging. See
 135                                 <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 136                                 for details. If this refers to a
 137                                 device node, a dependency on the
 138                                 respective device unit is
 139                                 automatically created. (See
 140                                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 141                                 for more information.) If this refers
 142                                 to a file, a dependency on the
 143                                 respective mount unit is automatically
 144                                 created. (See
 145                                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 146                                 for more information.) This option is
 147                                 mandatory.</para></listitem>
 148                         </varlistentry>
 149
 150                         <varlistentry>
 151                                 <term><varname>Priority=</varname></term>
 152
 153                                 <listitem><para>Swap priority to use
 154                                 when activating the swap device or
 155                                 file. This takes an integer. This
 156                                 setting is optional.</para></listitem>
 157                         </varlistentry>
 158
 159                         <varlistentry>
 160                                 <term><varname>TimeoutSec=</varname></term>
 161                                 <listitem><para>Configures the time to
 162                                 wait for the swapon command to
 163                                 finish. If a command does not exit
 164                                 within the configured time the swap
 165                                 will be considered failed and be shut
 166                                 down again. All commands still running
 167                                 will be terminated forcibly via
 168                                 SIGTERM, and after another delay of
 169                                 this time with SIGKILL. (See
 170                                 <option>KillMode=</option> below.)
 171                                 Takes a unit-less value in seconds, or
 172                                 a time span value such as "5min
 173                                 20s". Pass 0 to disable the timeout
 174                                 logic. Defaults to
 175                                 90s.</para></listitem>
 176                         </varlistentry>
 177
 178                         <varlistentry>
 179                                 <term><varname>KillMode=</varname></term>
 180                                 <listitem><para>Specifies how
 181                                 processes of this swap shall be
 182                                 killed. One of
 183                                 <option>control-group</option>,
 184                                 <option>process</option>,
 185                                 <option>none</option>.</para>
 186
 187                                 <para>This option is mostly equivalent
 188                                 to the <option>KillMode=</option>
 189                                 option of service files. See
 190                                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 191                                 for details.</para></listitem>
 192                         </varlistentry>
 193
 194                         <varlistentry>
 195                                 <term><varname>KillSignal=</varname></term>
 196                                 <listitem><para>Specifies which signal
 197                                 to use when killing a process of this
 198                                 swap. Defaults to SIGTERM.
 199                                 </para></listitem>
 200                         </varlistentry>
 201
 202                         <varlistentry>
 203                                 <term><varname>SendSIGKILL=</varname></term>
 204                                 <listitem><para>Specifies whether to
 205                                 send SIGKILL to remaining processes
 206                                 after a timeout, if the normal
 207                                 shutdown procedure left processes of
 208                                 the swap around. Takes a boolean
 209                                 value. Defaults to "yes".
 210                                 </para></listitem>
 211                         </varlistentry>
 212                 </variablelist>
 213         </refsect1>
 214
 215         <refsect1>
 216                   <title>See Also</title>
 217                   <para>
 218                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 219                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 220                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 221                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 222                           <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 223                           <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 224                           <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 225                           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 226                   </para>
 227         </refsect1>
 228
 229 </refentry>