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58 lines
2.6 KiB
XML
58 lines
2.6 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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version="5.0"
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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 <option>fileSystems</option>
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configuration option. For instance, the following definition causes NixOS to
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mount the Ext4 file system on device
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<filename>/dev/disk/by-label/data</filename> onto the mount point
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<filename>/data</filename>:
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<programlisting>
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<xref linkend="opt-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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This will create an entry in <filename>/etc/fstab</filename>, which will
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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 <link
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linkend="opt-fileSystems._name__.options">options</link>.
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<literal>"noauto"</literal> filesystems can be mounted explicitly using
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<command>systemctl</command> e.g. <command>systemctl start
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data.mount</command>.
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Mount points are created automatically if they don’t already exist. For
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<option><link linkend="opt-fileSystems._name__.device">device</link></option>,
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it’s best to use the topology-independent device aliases in
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<filename>/dev/disk/by-label</filename> and
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<filename>/dev/disk/by-uuid</filename>, as these don’t change if the
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topology changes (e.g. if a disk is moved to another IDE 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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(<option><link linkend="opt-fileSystems._name__.fsType">fsType</link></option>),
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since <command>mount</command> can usually detect the type and load the
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necessary kernel module automatically. However, if the file system is needed
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at early boot (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 to
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specify <option>fsType</option> to ensure that the kernel module is
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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, dropping
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you to the emergency shell. You can make a mount asynchronous and
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non-critical by adding
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<literal><link linkend="opt-fileSystems._name__.options">options</link> = [
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"nofail" ];</literal>.
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</para>
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</note>
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<xi:include href="luks-file-systems.xml" />
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</chapter>
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