man/systemd.mount.xml

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  23
  24 <refentry id="systemd.mount">
  25   <refentryinfo>
  26     <title>systemd.mount</title>
  27     <productname>systemd</productname>
  28
  29     <authorgroup>
  30       <author>
  31         <contrib>Developer</contrib>
  32         <firstname>Lennart</firstname>
  33         <surname>Poettering</surname>
  34         <email>lennart@poettering.net</email>
  35       </author>
  36     </authorgroup>
  37   </refentryinfo>
  38
  39   <refmeta>
  40     <refentrytitle>systemd.mount</refentrytitle>
  41     <manvolnum>5</manvolnum>
  42   </refmeta>
  43
  44   <refnamediv>
  45     <refname>systemd.mount</refname>
  46     <refpurpose>Mount unit configuration</refpurpose>
  47   </refnamediv>
  48
  49   <refsynopsisdiv>
  50     <para><filename><replaceable>mount</replaceable>.mount</filename></para>
  51   </refsynopsisdiv>
  52
  53   <refsect1>
  54     <title>Description</title>
  55
  56     <para>A unit configuration file whose name ends in
  57     <literal>.mount</literal> encodes information about a file system
  58     mount point controlled and supervised by systemd.</para>
  59
  60     <para>This man page lists the configuration options specific to
  61     this unit type. See
  62     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  63     for the common options of all unit configuration files. The common
  64     configuration items are configured in the generic [Unit] and
  65     [Install] sections. The mount specific configuration options are
  66     configured in the [Mount] section.</para>
  67
  68     <para>Additional options are listed in
  69     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  70     which define the execution environment the
  71     <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  72     binary is executed in, and in
  73     <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  74     which define the way the processes are terminated, and in
  75     <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  76     which configure resource control settings for the processes of the
  77     service. Note that the User= and Group= options are not
  78     particularly useful for mount units specifying a
  79     <literal>Type=</literal> option or using configuration not
  80     specified in <filename>/etc/fstab</filename>;
  81     <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  82     will refuse options that are not listed in
  83     <filename>/etc/fstab</filename> if it is not run as UID 0.</para>
  84
  85     <para>Mount units must be named after the mount point directories
  86     they control. Example: the mount point
  87     <filename noindex='true'>/home/lennart</filename> must be
  88     configured in a unit file <filename>home-lennart.mount</filename>.
  89     For details about the escaping logic used to convert a file system
  90     path to a unit name, see
  91     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
  92     Note that mount units cannot be templated.</para>
  93
  94     <para>Optionally, a mount unit may be accompanied by an automount
  95     unit, to allow on-demand or parallelized mounting. See
  96     <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  97
  98     <para>Mount points created at runtime (independently of unit files
  99     or <filename>/etc/fstab</filename>) will be monitored by systemd
 100     and appear like any other mount unit in systemd. See
 101     <filename>/proc/self/mountinfo</filename> description in
 102     <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 103     </para>
 104
 105     <para>Some file systems have special semantics as API file systems
 106     for kernel-to-userspace and userspace-to-userspace interfaces. Some
 107     of them may not be changed via mount units, and cannot be
 108     disabled. For a longer discussion see <ulink
 109     url="http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems">API
 110     File Systems</ulink>.</para>
 111   </refsect1>
 112
 113   <refsect1>
 114     <title>Automatic Dependencies</title>
 115
 116     <para>If a mount unit is beneath another mount unit in the file
 117     system hierarchy, both a requirement dependency and an ordering
 118     dependency between both units are created automatically.</para>
 119
 120     <para>Block device backed file systems automatically gain
 121     <varname>BindsTo=</varname> and <varname>After=</varname> type
 122     dependencies on the device unit encapsulating the block
 123     device (see below).</para>
 124
 125     <para>If traditional file system quota is enabled for a mount
 126     unit, automatic <varname>Wants=</varname> and
 127     <varname>Before=</varname> dependencies on
 128     <filename>systemd-quotacheck.service</filename> and
 129     <filename>quotaon.service</filename> are added.</para>
 130
 131     <para>For mount units with
 132     <varname>DefaultDependencies=yes</varname> (the default) a couple
 133     additional dependencies are added. Mount units referring to local
 134     file systems automatically gain an <varname>After=</varname>
 135     dependency on <filename>local-fs-pre.target</filename>. Network
 136     mount units automatically acquire <varname>After=</varname>
 137     dependencies on <filename>remote-fs-pre.target</filename>,
 138     <filename>network.target</filename> and
 139     <filename>network-online.target</filename>. Towards the latter a
 140     <varname>Wants=</varname> unit is added as well. Mount units
 141     referring to local and network file systems are distinguished by
 142     their file system type specification. In some cases this is not
 143     sufficient (for example network block device based mounts, such as
 144     iSCSI), in which case <option>_netdev</option> may be added to the
 145     mount option string of the unit, which forces systemd to consider the
 146     mount unit a network mount. Mount units (regardless if local or
 147     network) also acquire automatic <varname>Before=</varname> and
 148     <varname>Conflicts=</varname> on
 149     <filename>umount.target</filename> in order to be stopped
 150     during shutdown.</para>
 151
 152     <para>Additional implicit dependencies may be added as result of
 153     execution and resource control parameters as documented in
 154     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 155     and
 156     <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 157   </refsect1>
 158
 159   <refsect1>
 160     <title><filename>fstab</filename></title>
 161
 162     <para>Mount units may either be configured via unit files, or via
 163     <filename>/etc/fstab</filename> (see
 164     <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 165     for details). Mounts listed in <filename>/etc/fstab</filename>
 166     will be converted into native units dynamically at boot and when
 167     the configuration of the system manager is reloaded. In general,
 168     configuring mount points through <filename>/etc/fstab</filename>
 169     is the preferred approach. See
 170     <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 171     for details about the conversion.</para>
 172
 173     <para>When reading <filename>/etc/fstab</filename> a few special
 174     mount options are understood by systemd which influence how
 175     dependencies are created for mount points. systemd will create a
 176     dependency of type <varname>Wants=</varname> or
 177     <option>Requires</option> (see option <option>nofail</option>
 178     below), from either <filename>local-fs.target</filename> or
 179     <filename>remote-fs.target</filename>, depending whether the file
 180     system is local or remote.</para>
 181
 182     <variablelist class='fstab-options'>
 183
 184       <varlistentry>
 185         <term><option>x-systemd.requires=</option></term>
 186
 187         <listitem><para>Configures a <varname>Requires=</varname> and
 188         an <varname>After=</varname> dependency between the created
 189         mount unit and another systemd unit, such as a device or mount
 190         unit. The argument should be a unit name, or an absolute path
 191         to a device node or mount point.  This option may be specified
 192         more than once. This option is particularly useful for mount
 193         point declarations that need an additional device to be around
 194         (such as an external journal device for journal file systems)
 195         or an additional mount to be in place (such as an overlay file
 196         system that merges multiple mount points). See
 197         <varname>After=</varname> and <varname>Requires=</varname> in
 198         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 199         for details.</para></listitem>
 200       </varlistentry>
 201
 202       <varlistentry>
 203         <term><option>x-systemd.requires-mounts-for=</option></term>
 204
 205         <listitem><para>Configures a
 206         <varname>RequiresMountsFor=</varname> dependency between the
 207         created mount unit and other mount units. The argument must be
 208         an absolute path. This option may be specified more than once.
 209         See <varname>RequiresMountsFor=</varname> in
 210         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 211         for details.</para></listitem>
 212        </varlistentry>
 213
 214       <varlistentry>
 215         <term><option>x-systemd.automount</option></term>
 216
 217         <listitem><para>An automount unit will be created for the file
 218         system. See
 219         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 220         for details.</para></listitem>
 221       </varlistentry>
 222
 223       <varlistentry>
 224         <term><option>x-systemd.idle-timeout=</option></term>
 225
 226         <listitem><para>Configures the idle timeout of the
 227         automount unit. See <varname>TimeoutIdleSec=</varname> in
 228         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 229         for details.</para></listitem>
 230       </varlistentry>
 231
 232       <varlistentry>
 233         <term><option>x-systemd.device-timeout=</option></term>
 234
 235         <listitem><para>Configure how long systemd should wait for a
 236         device to show up before giving up on an entry from
 237         <filename>/etc/fstab</filename>. Specify a time in seconds or
 238         explicitly append a unit such as <literal>s</literal>,
 239         <literal>min</literal>, <literal>h</literal>,
 240         <literal>ms</literal>.</para>
 241
 242         <para>Note that this option can only be used in
 243         <filename>/etc/fstab</filename>, and will be
 244         ignored when part of the <varname>Options=</varname>
 245         setting in a unit file.</para>
 246         </listitem>
 247       </varlistentry>
 248
 249       <varlistentry>
 250         <term><option>noauto</option></term>
 251         <term><option>auto</option></term>
 252
 253         <listitem><para>With <option>noauto</option>, this mount will
 254         not be added as a dependency for
 255         <filename>local-fs.target</filename> or
 256         <filename>remote-fs.target</filename>. This means that it will
 257         not be mounted automatically during boot, unless it is pulled
 258         in by some other unit. The <option>auto</option> option has the
 259         opposite meaning and is the default.</para>
 260         </listitem>
 261       </varlistentry>
 262
 263       <varlistentry>
 264         <term><option>nofail</option></term>
 265
 266         <listitem><para>With <option>nofail</option>, this mount will
 267         be only wanted, not required, by
 268         <filename>local-fs.target</filename> or
 269         <filename>remote-fs.target</filename>. This means that the
 270         boot will continue even if this mount point is not mounted
 271         successfully.</para>
 272         </listitem>
 273       </varlistentry>
 274
 275       <varlistentry>
 276         <term><option>x-initrd.mount</option></term>
 277
 278         <listitem><para>An additional filesystem to be mounted in the
 279         initramfs. See <filename>initrd-fs.target</filename>
 280         description in
 281         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 282         </para></listitem>
 283       </varlistentry>
 284     </variablelist>
 285
 286     <para>If a mount point is configured in both
 287     <filename>/etc/fstab</filename> and a unit file that is stored
 288     below <filename>/usr</filename>, the former will take precedence.
 289     If the unit file is stored below <filename>/etc</filename>, it
 290     will take precedence. This means: native unit files take
 291     precedence over traditional configuration files, but this is
 292     superseded by the rule that configuration in
 293     <filename>/etc</filename> will always take precedence over
 294     configuration in <filename>/usr</filename>.</para>
 295   </refsect1>
 296
 297   <refsect1>
 298     <title>Options</title>
 299
 300     <para>Mount files must include a [Mount] section, which carries
 301     information about the file system mount points it supervises. A
 302     number of options that may be used in this section are shared with
 303     other unit types. These options are documented in
 304     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 305     and
 306     <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 307     The options specific to the [Mount] section of mount units are the
 308     following:</para>
 309
 310     <variablelist class='unit-directives'>
 311
 312       <varlistentry>
 313         <term><varname>What=</varname></term>
 314         <listitem><para>Takes an absolute path of a device node, file
 315         or other resource to mount. See
 316         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 317         for details. If this refers to a device node, a dependency on
 318         the respective device unit is automatically created. (See
 319         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 320         for more information.) This option is
 321         mandatory.</para></listitem>
 322       </varlistentry>
 323
 324       <varlistentry>
 325         <term><varname>Where=</varname></term>
 326         <listitem><para>Takes an absolute path of a directory of the
 327         mount point. If the mount point does not exist at the time of
 328         mounting, it is created. This string must be reflected in the
 329         unit filename. (See above.) This option is
 330         mandatory.</para></listitem>
 331       </varlistentry>
 332
 333       <varlistentry>
 334         <term><varname>Type=</varname></term>
 335         <listitem><para>Takes a string for the file system type. See
 336         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 337         for details. This setting is optional.</para></listitem>
 338       </varlistentry>
 339
 340       <varlistentry>
 341         <term><varname>Options=</varname></term>
 342
 343         <listitem><para>Mount options to use when mounting. This takes
 344         a comma-separated list of options. This setting is
 345         optional.</para></listitem>
 346       </varlistentry>
 347
 348       <varlistentry>
 349         <term><varname>SloppyOptions=</varname></term>
 350
 351         <listitem><para>Takes a boolean argument. If true, parsing of
 352         the options specified in <varname>Options=</varname> is
 353         relaxed, and unknown mount options are tolerated. This
 354         corresponds with
 355         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
 356         <parameter>-s</parameter> switch. Defaults to
 357         off.</para></listitem>
 358       </varlistentry>
 359
 360       <varlistentry>
 361         <term><varname>DirectoryMode=</varname></term>
 362         <listitem><para>Directories of mount points (and any parent
 363         directories) are automatically created if needed. This option
 364         specifies the file system access mode used when creating these
 365         directories. Takes an access mode in octal notation. Defaults
 366         to 0755.</para></listitem>
 367       </varlistentry>
 368
 369       <varlistentry>
 370         <term><varname>TimeoutSec=</varname></term>
 371         <listitem><para>Configures the time to wait for the mount
 372         command to finish. If a command does not exit within the
 373         configured time, the mount will be considered failed and be
 374         shut down again. All commands still running will be terminated
 375         forcibly via <constant>SIGTERM</constant>, and after another
 376         delay of this time with <constant>SIGKILL</constant>. (See
 377         <option>KillMode=</option> in
 378         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
 379         Takes a unit-less value in seconds, or a time span value such
 380         as "5min 20s". Pass 0 to disable the timeout logic. The
 381         default value is set from the manager configuration file's
 382         <varname>DefaultTimeoutStart=</varname>
 383         variable.</para></listitem>
 384       </varlistentry>
 385     </variablelist>
 386
 387     <para>Check
 388     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 389     and
 390     <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 391     for more settings.</para>
 392   </refsect1>
 393
 394   <refsect1>
 395       <title>See Also</title>
 396       <para>
 397         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 398         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 399         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 400         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 401         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 402         <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 403         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 404         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 405         <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 406         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 407         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 408         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 409       </para>
 410   </refsect1>
 411
 412 </refentry>