NAME
systemd.mount - Mount unit configurationSYNOPSIS
mount.mountDESCRIPTION
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) program 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 options User= and Group= are not useful for mount units. systemd passes two parameters to mount(8); the values of What= and Where=. When invoked in this way, mount(8) does not read any options from /etc/fstab, and must be 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 symlinks to its unit file. 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]. The systemd-mount(1) command allows creating .mount and .automount units dynamically and transiently from the command line.AUTOMATIC DEPENDENCIES
Implicit Dependencies
The following dependencies are implicitly added:•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.
•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).
Default Dependencies
The following dependencies are added unless DefaultDependencies=no is set:•All mount units acquire automatic
Before= and Conflicts= on umount.target in order to be stopped
during shutdown.
•Mount units referring to local file
systems automatically gain an After= dependency on local-fs-pre.target,
and a Before= dependency on local-fs.target unless nofail mount
option is set.
•Network mount units automatically
acquire After= dependencies on remote-fs-pre.target, network.target and
network-online.target, and gain a Before= dependency on
remote-fs.target unless nofail mount option is set. 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.
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 to manage mounts for humans. For tooling, writing mount units should be preferred over editing /etc/fstab. See systemd-fstab-generator(8) for details about the conversion from /etc/fstab to mount units. The NFS mount option bg for NFS background mounts as documented in nfs(5) is detected by systemd-fstab-generator and the options are transformed so that systemd fulfills the job-control implications of that option. Specifically systemd-fstab-generator acts as though "x-systemd.mount-timeout=infinity,retry=10000" was prepended to the option list, and "fg,nofail" was appended. Depending on specific requirements, it may be appropriate to provide some of these options explicitly, or to make use of the "x-systemd.automount" option described below instead of using "bg". 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.
Note that this option always applies to the created mount unit only regardless
whether x-systemd.automount has been specified.
x-systemd.before=, x-systemd.after=
In the created mount unit, configures a
Before= or After= dependency on another systemd unit, such as a
mount unit. The argument should be a unit name or an absolute path to a mount
point. This option may be specified more than once. This option is
particularly useful for mount point declarations with nofail option
that are mounted asynchronously but need to be mounted before or after some
unit start, for example, before local-fs.target unit. See Before= and
After= in systemd.unit(5) for details.
Note that these options always apply to the created mount unit only regardless
whether x-systemd.automount has been specified.
x-systemd.wanted-by=, x-systemd.required-by=
In the created mount unit, configures a
WantedBy= or RequiredBy= dependency on another unit. This option
may be specified more than once. If this is specified, the normal automatic
dependencies on the created mount unit, e.g., local-fs.target, are not
automatically created. See WantedBy= and RequiredBy= 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.device-bound
The block device backed file system will be
upgraded to BindsTo= dependency. This option is only useful when
mounting file systems manually with mount(8) as the default dependency
in this case is Requires=. This option is already implied by entries in
/etc/fstab or by mount units.
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.
x-systemd.makefs
The file system will be initialized on the
device. If the device is not "empty", i.e. it contains any
signature, the operation will be skipped. It is hence expected that this
option remains set even after the device has been initialized.
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 systemd-makefs@.service(8).
wipefs(8) may be used to remove any signatures from a block device to
force x-systemd.makefs to reinitialize the device.
x-systemd.growfs
The file system will be grown to occupy the
full block device. If the file system is already at maximum size, no action
will be performed. It is hence expected that this option remains set even
after the file system has been grown. Only certain file system types are
supported, see systemd-makefs@.service(8) for details.
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.rw-only
If a mount operation fails to mount the file
system read-write, it normally tries mounting the file system read-only
instead. This option disables that behaviour, and causes the mount to fail
immediately instead. This option is translated into the ReadWriteOnly=
setting in a unit file.
_netdev
Normally the file system type is used to
determine if a mount is a "network mount", i.e. if it should only be
started after the network is available. Using this option overrides this
detection and specifies that the mount requires network.
Network mount units are ordered between remote-fs-pre.target and
remote-fs.target, instead of local-fs-pre.target and local-fs.target. They
also pull in network-online.target and are ordered after it and
network.target.
noauto, auto
With noauto, the mount unit 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.
Note that if x-systemd.automount (see above) is used, neither auto
nor noauto have any effect. The matching automount unit will be added
as a dependency to the appropriate target.
nofail
With nofail, this mount will be only
wanted, not required, by local-fs.target or remote-fs.target. Moreover the
mount unit is not ordered before these target units. This means that the boot
will continue without waiting for the mount unit and regardless whether the
mount point can be mounted successfully.
x-initrd.mount
An additional filesystem to be mounted in the
initrd. 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 unit files may include [Unit] and [Install] sections, which are described in systemd.unit(5). Mount unit 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. Note that the usual specifier expansion is applied to this setting,
literal percent characters should hence be written as "%%". If this
mount is a bind mount and the specified path does not exist yet it is created
as directory.
Where=
Takes an absolute path of a file or directory
for the mount point; in particular, the destination cannot be a symbolic link.
If the mount point does not exist at the time of mounting, it is created as
either a directory or a file. The former is the usual case; the latter is done
only if this mount is a bind mount and the source ( What=) is not a
directory. 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. Note that the
usual specifier expansion is applied to this setting, literal percent
characters should hence be written as "%%".
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.
ReadWriteOnly=
Takes a boolean argument. If false, a mount
point that shall be mounted read-write but cannot be mounted so is retried to
be mounted read-only. If true the operation will fail immediately after the
read-write mount attempt did not succeed. This corresponds with
mount(8)'s -w 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 DefaultTimeoutStartSec= option in
systemd-system.conf(5).
Check systemd.unit(5), systemd.exec(5), and systemd.kill(5)
for more settings.
SEE ALSO
systemd(1), systemctl(1), systemd-system.conf(5), 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), systemd-mount(1)NOTES
- 1.
- API File Systems
systemd 252 |