systemd.swapsystemdDeveloperLennartPoetteringlennart@poettering.netsystemd.swap5systemd.swapSwap unit configurationswap.swapDescriptionA 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.unit5
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.exec5,
which define the execution environment the
swapon8
binary is executed in, and in
systemd.kill5,
which define the way the processes are terminated, and in
systemd.resource-control5,
which configure resource control settings for the processes of the
service.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.unit5.All swap units automatically get the appropriate
dependencies on the devices or on the mount points of the files
they are activated from.Swap units with DefaultDependencies=
enabled implicitly acquire a conflicting dependency to
umount.target so that they are deactivated at
shutdown.<filename>fstab</filename>Swap units may either be configured via unit files, or via
/etc/fstab (see
fstab5
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-generator8
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.With 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. Option has the
opposite meaning and is the default.With 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.OptionsSwap 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.exec5
and
systemd.kill5.
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
swapon8
for details. If this refers to a device node, a dependency on
the respective device unit is automatically created. (See
systemd.device5
for more information.) If this refers to a file, a dependency
on the respective mount unit is automatically created. (See
systemd.mount5
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 priotiry is set by in the
Options= option.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
swapon8
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
in
systemd.kill5.)
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.conf5).
Check
systemd.exec5
and
systemd.kill5
for more settings.See Alsosystemd1,
systemctl1,
systemd.unit5,
systemd.exec5,
systemd.kill5,
systemd.resource-control5,
systemd.device5,
systemd.mount5,
swapon8,
systemd-fstab-generator8,
systemd.directives7