systemd.swap(5) - Swap unit configuration

[amurleopard]

SYSTEMD.SWAP(5) 		 systemd.swap		       SYSTEMD.SWAP(5)

NAME
       systemd.swap - Swap unit configuration

SYNOPSIS
       swap.swap

DESCRIPTION
       A unit configuration file whose name ends in ".swap" encodes
       information about a swap device or file for memory paging controlled
       and supervised by systemd.

       This man page lists the configuration options specific to this unit
       type. See systemd.unit(5) 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.

       Additional options are listed in systemd.exec(5), which define the
       execution environment the swapon(8) binary is executed in, in
       systemd.kill(5), which define the way the these processes are
       terminated, and in systemd.resource-control(5), which configure
       resource control settings for these processes of the unit.

       Swap units must be named after the devices or files they control.
       Example: the swap device /dev/sda5 must be configured in a unit file
       dev-sda5.swap. For details about the escaping logic used to convert a
       file system path to a unit name, see systemd.unit(5).

AUTOMATIC DEPENDENCIES
       All swap units automatically get the BindsTo= and After= dependencies
       on the device units or the mount units of the files they are activated
       from.

       Swap units with DefaultDependencies= enabled implicitly acquire a
       Conflicts= and an After= dependency on umount.target so that they are
       deactivated at shutdown, unless DefaultDependencies=no is specified.

       Additional implicit dependencies may be added as result of execution
       and resource control parameters as documented in systemd.exec(5) and
       systemd.resource-control(5).

FSTAB
       Swap units may either be configured via unit files, or via /etc/fstab
       (see fstab(5) for details). Swaps listed in /etc/fstab will be
       converted into native units dynamically at boot and when the
       configuration of the system manager is reloaded. See systemd-fstab-
       generator(8) for details about the conversion.

       If a swap device or file is configured in both /etc/fstab and a unit
       file, the configuration in the latter takes precedence.

       When reading /etc/fstab, a few special options are understood by
       systemd which influence how dependencies are created for swap units.

       noauto, auto
	   With noauto, the swap unit will not be added as a dependency for
	   swap.target. This means that it will not be activated automatically
	   during boot, unless it is pulled in by some other unit. The auto
	   option has the opposite meaning and is the default.

       nofail
	   With nofail, the swap unit will be only wanted, not required by
	   swap.target. This means that the boot will continue even if this
	   swap device is not activated successfully.

OPTIONS
       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 systemd.exec(5) and systemd.kill(5). The options
       specific to the [Swap] section of swap units are the following:

       What=
	   Takes an absolute path of a device node or file to use for paging.
	   See swapon(8) for details. If this refers to a device node, a
	   dependency on the respective device unit is automatically created.
	   (See systemd.device(5) for more information.) If this refers to a
	   file, a dependency on the respective mount unit is automatically
	   created. (See systemd.mount(5) for more information.) This option
	   is mandatory.

       Priority=
	   Swap priority to use when activating the swap device or file. This
	   takes an integer. This setting is optional and ignored when the
	   priority is set by pri= in the Options= key.

       Options=
	   May contain an option string for the swap device. This may be used
	   for controlling discard options among other functionality, if the
	   swap backing device supports the discard or trim operation. (See
	   swapon(8) for more information.)

       TimeoutSec=
	   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 SIGTERM, and after another
	   delay of this time with SIGKILL. (See KillMode= in
	   systemd.kill(5).) 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 DefaultTimeoutStartSec= from the manager
	   configuration file (see systemd-system.conf(5)).

       Check systemd.exec(5) and systemd.kill(5) for more settings.

SEE ALSO
       systemd(1), systemctl(1), systemd.unit(5), systemd.exec(5),
       systemd.kill(5), systemd.resource-control(5), systemd.device(5),
       systemd.mount(5), swapon(8), systemd-fstab-generator(8),
       systemd.directives(7)

systemd 229						       SYSTEMD.SWAP(5)