55 lines
2.6 KiB
XML
55 lines
2.6 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude" xml:id="ch-file-systems">
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<title>File Systems</title>
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<para>
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You can define file systems using the <literal>fileSystems</literal>
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configuration option. For instance, the following definition causes
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NixOS to mount the Ext4 file system on device
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<literal>/dev/disk/by-label/data</literal> onto the mount point
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<literal>/data</literal>:
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</para>
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<programlisting language="bash">
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fileSystems."/data" =
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{ device = "/dev/disk/by-label/data";
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fsType = "ext4";
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};
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</programlisting>
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<para>
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This will create an entry in <literal>/etc/fstab</literal>, which
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will generate a corresponding
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<link xlink:href="https://www.freedesktop.org/software/systemd/man/systemd.mount.html">systemd.mount</link>
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unit via
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<link xlink:href="https://www.freedesktop.org/software/systemd/man/systemd-fstab-generator.html">systemd-fstab-generator</link>.
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The filesystem will be mounted automatically unless
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<literal>"noauto"</literal> is present in
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<link linkend="opt-fileSystems._name_.options">options</link>.
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<literal>"noauto"</literal> filesystems can be mounted
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explicitly using <literal>systemctl</literal> e.g.
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<literal>systemctl start data.mount</literal>. Mount points are
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created automatically if they don’t already exist. For
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<literal>device</literal>, it’s best to use the topology-independent
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device aliases in <literal>/dev/disk/by-label</literal> and
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<literal>/dev/disk/by-uuid</literal>, as these don’t change if the
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topology changes (e.g. if a disk is moved to another IDE
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controller).
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</para>
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<para>
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You can usually omit the file system type
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(<literal>fsType</literal>), since <literal>mount</literal> can
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usually detect the type and load the necessary kernel module
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automatically. However, if the file system is needed at early boot
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(in the initial ramdisk) and is not <literal>ext2</literal>,
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<literal>ext3</literal> or <literal>ext4</literal>, then it’s best
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to specify <literal>fsType</literal> to ensure that the kernel
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module is available.
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</para>
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<note>
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<para>
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System startup will fail if any of the filesystems fails to mount,
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dropping you to the emergency shell. You can make a mount
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asynchronous and non-critical by adding
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<literal>options = [ "nofail" ];</literal>.
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</para>
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</note>
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<xi:include href="luks-file-systems.section.xml" />
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<xi:include href="sshfs-file-systems.section.xml" />
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</chapter>
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