systemd/man/systemd.mount.xml
Zbigniew Jędrzejewski-Szmek 5607d856b8 swap: restore support for nofail
systemd stops adding automatic dependencies on swap.target to swap
units. If a dependency is required, it has to be added by unit
configuration. fstab-generator did that already, except that now it is
modified to create a Requires or Wants type dependency, depending on
whether nofail is specified in /etc/fstab. This makes .swap units
obey the nofail/noauto options more or less the same as .mount units.

Documentation is extended to clarify that, and to make
systemd.mount(5) and system.swap(5) more similar. The gist is not
changed, because current behaviour actually matches existing
documentation.

https://bugs.freedesktop.org/show_bug.cgi?id=86488
2014-11-26 15:17:07 -05:00

371 lines
20 KiB
XML

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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<refentry id="systemd.mount">
<refentryinfo>
<title>systemd.mount</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd.mount</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.mount</refname>
<refpurpose>Mount unit configuration</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename><replaceable>mount</replaceable>.mount</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>A unit configuration file whose name ends in
<literal>.mount</literal> encodes information about
a file system mount point controlled and supervised by
systemd.</para>
<para>This man page lists the configuration options
specific to this unit type. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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.</para>
<para>Additional options are listed in
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
which define the execution environment the
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
binary is executed in, and in
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
which define the way the processes are terminated, and
in
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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 <literal>Type=</literal> option or
using configuration not specified in
<filename>/etc/fstab</filename>;
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
will refuse options that are not listed in
<filename>/etc/fstab</filename> if it is not run as
UID 0.</para>
<para>Mount units must be named after the mount point
directories they control. Example: the mount point
<filename noindex='true'>/home/lennart</filename> must be configured
in a unit file
<filename>home-lennart.mount</filename>. For details
about the escaping logic used to convert a file system
path to a unit name, see
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
<para>Optionally, a mount unit may be accompanied by
an automount unit, to allow on-demand or parallelized
mounting. See
<citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
<para>If a mount point is beneath another mount point
in the file system hierarchy, a dependency between both
units is created automatically.</para>
<para>Mount points created at runtime (independently of
unit files or <filename>/etc/fstab</filename>) will be
monitored by systemd and appear like any other mount
unit in systemd.
See <filename>/proc/self/mountinfo</filename> description
in <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>Some file systems have special semantics as API
file systems for kernel-to-userspace and
userspace-to-userpace interfaces. Some of them may not
be changed via mount units, and cannot be disabled.
For a longer discussion see <ulink
url="http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems">API
File Systems</ulink>.</para>
</refsect1>
<refsect1>
<title><filename>fstab</filename></title>
<para>Mount units may either be configured via unit
files, or via <filename>/etc/fstab</filename> (see
<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details). Mounts listed in
<filename>/etc/fstab</filename> 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
<filename>/etc/fstab</filename> is the preferred
approach. See
<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details about the conversion.</para>
<para>When reading <filename>/etc/fstab</filename> 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
<option>Wants</option> or <option>Requires</option>
(see option <option>nofail</option> below), from
either <filename>local-fs.target</filename> or
<filename>remote-fs.target</filename>, depending
whether the file system is local or remote.</para>
<variablelist class='fstab-options'>
<varlistentry>
<term><option>x-systemd.automount</option></term>
<listitem><para>An automount unit will be created
for the file system. See
<citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>x-systemd.device-timeout=</option></term>
<listitem><para>Configure how long systemd should
wait for a device to show up before giving up on
an entry from
<filename>/etc/fstab</filename>. Specify a time in
seconds or explicitly append a unit as
<literal>s</literal>, <literal>min</literal>,
<literal>h</literal>,
<literal>ms</literal>.</para>
<para>Note that this option can only be used in
<filename>/etc/fstab</filename>, and will be
ignored when part of <varname>Options=</varname>
setting in a unit file.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>noauto</option></term>
<term><option>auto</option></term>
<listitem><para>With <option>noauto</option>, this
mount will not be added as a dependency for
<filename>local-fs.target</filename> or
<filename>remote-fs.target</filename>. This means
that it will not be mounted automatically during
boot, unless it is pulled in by some other
unit. Option <option>auto</option> has the
opposite meaning and is the default.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>nofail</option></term>
<term><option>fail</option></term>
<listitem><para>With <option>nofail</option> this
mount will be only wanted, not required, by
<filename>local-fs.target</filename> or
<filename>remote-fs.target</filename>. This means
that the boot will continue even if this mount
point is not mounted successfully. Option
<option>fail</option> has the opposite meaning and
is the default.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>x-initrd.mount</option></term>
<listitem><para>An additional filesystem to be
mounted in the initramfs. See
<filename>initrd-fs.target</filename> description
in
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para></listitem>
</varlistentry>
</variablelist>
<para>If a mount point is configured in both
<filename>/etc/fstab</filename> and a unit file that
is stored below <filename>/usr</filename>, the former
will take precedence. If the unit file is stored below
<filename>/etc</filename>, 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
<filename>/etc</filename> will always take precedence
over configuration in
<filename>/usr</filename>.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>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
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
options specific to the [Mount] section of mount
units are the following:</para>
<variablelist class='unit-directives'>
<varlistentry>
<term><varname>What=</varname></term>
<listitem><para>Takes an absolute path
of a device node, file or other
resource to mount. See
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details. If this refers to a
device node, a dependency on the
respective device unit is
automatically created. (See
<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.)
This option is
mandatory.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Where=</varname></term>
<listitem><para>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.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Type=</varname></term>
<listitem><para>Takes a string for the
file system type. See
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details. This setting is
optional.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Options=</varname></term>
<listitem><para>Mount options to use
when mounting. This takes a
comma-separated list of options. This
setting is optional.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SloppyOptions=</varname></term>
<listitem><para>Takes a boolean
argument. If true, parsing of the
options specified in
<varname>Options=</varname> is
relaxed, and unknown mount options are
tolerated. This corresponds with
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
<parameter>-s</parameter>
switch. Defaults to
off.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>DirectoryMode=</varname></term>
<listitem><para>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.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>TimeoutSec=</varname></term>
<listitem><para>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
<constant>SIGTERM</constant>, and after another delay of
this time with <constant>SIGKILL</constant>. (See
<option>KillMode=</option> in
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
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 <varname>DefaultTimeoutStart=</varname> variable.</para></listitem>
</varlistentry>
</variablelist>
<para>Check
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more settings.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>