3 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
5 SPDX-License-Identifier: LGPL-2.1+
7 Copyright 2016 Lennart Poettering
9 <refentry id=
"systemd-volatile-root.service">
12 <title>systemd-volatile-root.service
</title>
13 <productname>systemd
</productname>
17 <contrib>Developer
</contrib>
18 <firstname>Lennart
</firstname>
19 <surname>Poettering
</surname>
20 <email>lennart@poettering.net
</email>
26 <refentrytitle>systemd-volatile-root.service
</refentrytitle>
27 <manvolnum>8</manvolnum>
31 <refname>systemd-volatile-root.service
</refname>
32 <refname>systemd-volatile-root
</refname>
33 <refpurpose>Make the root file system volatile
</refpurpose>
37 <para><filename>systemd-volatile-root.service
</filename></para>
38 <para><filename>/usr/lib/systemd/systemd-volatile-root
</filename></para>
42 <title>Description
</title>
44 <para><filename>systemd-volatile-root.service
</filename> is a service that replaces the root directory with a
45 volatile memory file system (
<literal>tmpfs
</literal>), mounting the original (non-volatile)
46 <filename>/usr
</filename> inside it read-only. This way, vendor data from
<filename>/usr
</filename> is available as
47 usual, but all configuration data in
<filename>/etc
</filename>, all state data in
<filename>/var
</filename> and all
48 other resources stored directly under the root directory are reset on boot and lost at shutdown, enabling fully
49 stateless systems.
</para>
51 <para>This service is only enabled if full volatile mode is selected, for example by specifying
52 <literal>systemd.volatile=yes
</literal> on the kernel command line. This service runs only in the initial RAM disk
53 (
"initrd"), before the system transitions to the host's root directory. Note that this service is not used if
54 <literal>systemd.volatile=state
</literal> is used, as in that mode the root directory is non-volatile.
</para>
58 <title>See Also
</title>
60 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
61 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
62 <citerefentry><refentrytitle>kernel-command-line
</refentrytitle><manvolnum>7</manvolnum></citerefentry>