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