Provided by:
systemd_232-21ubuntu2_amd64 
NAME
systemd.mount - Mount unit configuration
SYNOPSIS
mount.mount
DESCRIPTION
A unit configuration file whose name ends in ".mount" encodes
information about a file system mount point 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 mount specific
configuration options are configured in the [Mount] section.
Additional options are listed in systemd.exec(5), which define the
execution environment the mount(8) binary is executed in, and in
systemd.kill(5), which define the way the processes are terminated, and
in systemd.resource-control(5), which configure resource control
settings for the processes of the service. Note that the User= and
Group= options are not particularly useful for mount units specifying a
"Type=" option or using configuration not specified in /etc/fstab;
mount(8) will refuse options that are not listed in /etc/fstab if it is
not run as UID 0.
Mount units must be named after the mount point directories they
control. Example: the mount point /home/lennart must be configured in a
unit file home-lennart.mount. For details about the escaping logic used
to convert a file system path to a unit name, see systemd.unit(5). Note
that mount units cannot be templated, nor is possible to add multiple
names to a mount unit by creating additional symlinks to it.
Optionally, a mount unit may be accompanied by an automount unit, to
allow on-demand or parallelized mounting. See systemd.automount(5).
Mount points created at runtime (independently of unit files or
/etc/fstab) will be monitored by systemd and appear like any other
mount unit in systemd. See /proc/self/mountinfo description in proc(5).
Some file systems have special semantics as API file systems for
kernel-to-userspace and userspace-to-userspace interfaces. Some of them
may not be changed via mount units, and cannot be disabled. For a
longer discussion see API File Systems[1].
AUTOMATIC DEPENDENCIES
If a mount unit is beneath another mount unit in the file system
hierarchy, both a requirement dependency and an ordering dependency
between both units are created automatically.
Block device backed file systems automatically gain BindsTo= and After=
type dependencies on the device unit encapsulating the block device
(see below).
If traditional file system quota is enabled for a mount unit, automatic
Wants= and Before= dependencies on systemd-quotacheck.service and
quotaon.service are added.
For mount units with DefaultDependencies=yes in the "[Unit]" section
(the default) a couple additional dependencies are added. Mount units
referring to local file systems automatically gain an After= dependency
on local-fs-pre.target. Network mount units automatically acquire
After= dependencies on remote-fs-pre.target, network.target and
network-online.target. Towards the latter a Wants= unit is added as
well. Mount units referring to local and network file systems are
distinguished by their file system type specification. In some cases
this is not sufficient (for example network block device based mounts,
such as iSCSI), in which case _netdev may be added to the mount option
string of the unit, which forces systemd to consider the mount unit a
network mount. Mount units (regardless if local or network) also
acquire automatic Before= and Conflicts= on umount.target in order to
be stopped during shutdown.
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
Mount units may either be configured via unit files, or via /etc/fstab
(see fstab(5) for details). Mounts listed in /etc/fstab will be
converted into native units dynamically at boot and when the
configuration of the system manager is reloaded. In general,
configuring mount points through /etc/fstab is the preferred approach.
See systemd-fstab-generator(8) for details about the conversion.
The NFS mount option bg for NFS background mounts as documented in
nfs(5) is not supported in /etc/fstab entries. The systemd mount option
nofail provides similar functionality and should be used instead.
When reading /etc/fstab a few special mount options are understood by
systemd which influence how dependencies are created for mount points.
systemd will create a dependency of type Wants= or Requires (see option
nofail below), from either local-fs.target or remote-fs.target,
depending whether the file system is local or remote.
x-systemd.requires=
Configures a Requires= and an After= dependency between the created
mount unit and another systemd unit, such as a device or mount
unit. The argument should be a unit name, or an absolute path to a
device node or mount point. This option may be specified more than
once. This option is particularly useful for mount point
declarations that need an additional device to be around (such as
an external journal device for journal file systems) or an
additional mount to be in place (such as an overlay file system
that merges multiple mount points). See After= and Requires= in
systemd.unit(5) for details.
x-systemd.requires-mounts-for=
Configures a RequiresMountsFor= dependency between the created
mount unit and other mount units. The argument must be an absolute
path. This option may be specified more than once. See
RequiresMountsFor= in systemd.unit(5) for details.
x-systemd.automount
An automount unit will be created for the file system. See
systemd.automount(5) for details.
x-systemd.idle-timeout=
Configures the idle timeout of the automount unit. See
TimeoutIdleSec= in systemd.automount(5) for details.
x-systemd.device-timeout=
Configure how long systemd should wait for a device to show up
before giving up on an entry from /etc/fstab. Specify a time in
seconds or explicitly append a unit such as "s", "min", "h", "ms".
Note that this option can only be used in /etc/fstab, and will be
ignored when part of the Options= setting in a unit file.
x-systemd.mount-timeout=
Configure how long systemd should wait for the mount command to
finish before giving up on an entry from /etc/fstab. Specify a time
in seconds or explicitly append a unit such as "s", "min", "h",
"ms".
Note that this option can only be used in /etc/fstab, and will be
ignored when part of the Options= setting in a unit file.
See TimeoutSec= below for details.
noauto, auto
With noauto, this mount will not be added as a dependency for
local-fs.target or remote-fs.target. This means that it will not be
mounted 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, this mount will be only wanted, not required, by
local-fs.target or remote-fs.target. This means that the boot will
continue even if this mount point is not mounted successfully.
x-initrd.mount
An additional filesystem to be mounted in the initramfs. See
initrd-fs.target description in systemd.special(7).
If a mount point is configured in both /etc/fstab and a unit file that
is stored below /usr, the former will take precedence. If the unit file
is stored below /etc, it will take precedence. This means: native unit
files take precedence over traditional configuration files, but this is
superseded by the rule that configuration in /etc will always take
precedence over configuration in /usr.
OPTIONS
Mount files must include a [Mount] section, which carries information
about the file system mount points 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 [Mount] section of mount units are the
following:
What=
Takes an absolute path of a device node, file or other resource to
mount. See mount(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.) This option is
mandatory.
Where=
Takes an absolute path of a directory of the mount point. If the
mount point does not exist at the time of mounting, it is created.
This string must be reflected in the unit filename. (See above.)
This option is mandatory.
Type=
Takes a string for the file system type. See mount(8) for details.
This setting is optional.
Options=
Mount options to use when mounting. This takes a comma-separated
list of options. This setting is optional.
SloppyOptions=
Takes a boolean argument. If true, parsing of the options specified
in Options= is relaxed, and unknown mount options are tolerated.
This corresponds with mount(8)'s -s switch. Defaults to off.
LazyUnmount=
Takes a boolean argument. If true, detach the filesystem from the
filesystem hierarchy at time of the unmount operation, and clean up
all references to the filesystem as soon as they are not busy
anymore. This corresponds with umount(8)'s -l switch. Defaults to
off.
ForceUnmount=
Takes a boolean argument. If true, force an unmount (in case of an
unreachable NFS system). This corresponds with umount(8)'s -f
switch. Defaults to off.
DirectoryMode=
Directories of mount points (and any parent directories) are
automatically created if needed. This option specifies the file
system access mode used when creating these directories. Takes an
access mode in octal notation. Defaults to 0755.
TimeoutSec=
Configures the time to wait for the mount command to finish. If a
command does not exit within the configured time, the mount 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.
The default value is set from the manager configuration file's
DefaultTimeoutStartSec= variable.
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.service(5),
systemd.device(5), proc(5), mount(8), systemd-fstab-generator(8),
systemd.directives(7)
NOTES
1. API File Systems
http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems