| SYSTEMD.MOUNT(5) | systemd.mount | SYSTEMD.MOUNT(5) |
.SH "NAME" systemd.mount - Mount unit configuration
.SH "SYNOPSIS"
.PP mount.mount
.SH "DESCRIPTION"
.PP A unit configuration file whose name ends in .mount encodes information
about a file system mount point controlled and supervised by systemd.
.PP 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.
.PP 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.
.PP 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.
.PP 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.
.PP Optionally, a mount unit may be accompanied by an automount unit, to
allow on-demand or parallelized mounting. See
systemd.automount(5).
.PP 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).
.PP 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].
.PP The systemd-mount(1) command allows creating .mount and .automount
units dynamically and transiently from the command line.
.SH "AUTOMATIC DEPENDENCIES"
.SS "Implicit Dependencies"
.PP The following dependencies are implicitly added:
.SS "Default Dependencies"
.PP The following dependencies are added unless DefaultDependencies=no
is set:
Additionally, an After= dependency on swap.target is added when the
file system type is tmpfs.
.RE
.PP 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.
.SH "FSTAB"
.PP 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.
.PP 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.
.PP 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.
.PP 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.
Added in version 220.
.RE
.PP x-systemd.wants=
Configures a Wants= and an After= dependency between the
created mount unit and another systemd unit, similar to the
x-systemd.requires= option.
Added in version 257.
.RE
.PP 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.
Added in version 233.
.RE
.PP 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 default dependencies (see above)
other than umount.target on the created mount unit, e.g. local-fs.target,
are not automatically created. Hence it is likely that some ordering
dependencies need to be set up manually through x-systemd.before= and
x-systemd.after=. See WantedBy= and RequiredBy= in
systemd.unit(5) for details.
Added in version 245.
.RE
.PP x-systemd.wants-mounts-for=,
x-systemd.requires-mounts-for=
Configures a RequiresMountsFor= or WantsMountsFor= 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= or WantsMountsFor= in
systemd.unit(5) for details.
Added in version 220.
.RE
.PP x-systemd.graceful-option=
Additional mount option that shall be appended if supported by the kernel.
This may be used to configure mount options that are optional and only
enabled on kernels that support them. Note that this is supported only for
native kernel mount options (i.e. explicitly not for mount options
implemented in userspace, such as those processed by /usr/bin/mount
itself, by FUSE or by mount helpers such as mount.nfs). This option
may be specified more than once.
Added in version 258.
.RE
.PP x-systemd.device-bound=
Takes a boolean argument. If true or no argument, a BindsTo=
dependency on the backing device is set. If false, the mount unit is not
stopped no matter whether the backing device is still present. This is
useful when the file system is backed by volume managers. If not set, and
the mount comes from unit fragments, i.e. generated from /etc/fstab by
systemd-fstab-generator(8) or loaded from a manually configured mount
unit, a combination of Requires= and StopPropagatedFrom=
dependencies is set on the backing device, otherwise only Requires=
is used.
Added in version 233.
.RE
.PP x-systemd.automount
An automount unit will be created for the file system. See
systemd.automount(5) for details.
Added in version 215.
.RE
.PP x-systemd.idle-timeout=
Configures the idle timeout of the automount unit. See TimeoutIdleSec=
in systemd.automount(5) for details.
Added in version 220.
.RE
.PP 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.
Added in version 215.
.RE
.PP 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.
Added in version 233.
.RE
.PP 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.
Added in version 236.
.RE
.PP 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.
Added in version 236.
.RE
.PP x-systemd.pcrfs
Measures file system identity information (mount point, type, label, UUID,
partition label, partition UUID) into PCR 15 after the file system has been
mounted. This ensures the systemd-pcrfs@.service(8) or
systemd-pcrfs-root.service services are pulled in by the mount unit.
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. It is also implied
for the root and /usr/ partitions discovered by
systemd-gpt-auto-generator(8).
Added in version 253.
.RE
.PP x-systemd.validatefs
Validates mount constraint metadata of the mounted file system after mounting
it. This ensures the systemd-validatefs@.service(8) service is pulled
in by the mount unit.
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. It is also implied
for all partitions discovered by systemd-gpt-auto-generator(8).
Added in version 258.
.RE
.PP 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.
Added in version 246.
.RE
.PP _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.
Added in version 235.
.RE
.PP 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.
Added in version 215.
.RE
.PP 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.
Added in version 215.
.RE
.PP x-initrd.mount
An additional filesystem to be mounted in the initrd. See initrd-fs.target
description in systemd.special(7). This is both an indicator to the
initrd to mount this partition early and an indicator to the host to leave
the partition mounted until final shutdown. Or in other words, if this flag
is set it is assumed the mount shall be active during the entire regular
runtime of the system, i.e. established before the initrd transitions into
the host all the way until the host transitions to the final shutdown
phase.
Added in version 215.
.RE
.PP 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/.
.SH "OPTIONS"
.PP Mount unit files may include [Unit] and [Install] sections, which are
described in systemd.unit(5).
.PP 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),
systemd.kill(5) and systemd.resource-control(5). The options
specific to the [Mount] section of mount units are the following:
.PP What=
Takes an absolute path or a fstab-style identifier 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.
.RE
.PP 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.
.RE
.PP Type=
Takes a string for the file system type. See mount(8) for details.
This setting is optional.
If the type is overlay, and upperdir= or workdir= are specified as options
and the directories do not exist, they will be created.
.RE
.PP 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 %%.
.RE
.PP 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.
Added in version 215.
.RE
.PP 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.
Added in version 232.
.RE
.PP 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.
Added in version 246.
.RE
.PP 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.
Added in version 232.
.RE
.PP 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.
.RE
.PP 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).
.RE
.PP Check systemd.unit(5), systemd.exec(5), and
systemd.kill(5) for more settings.
.SH "SEE ALSO"
.PP 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 262.2 |