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 This file is part of systemd.
9 Copyright 2016 Lennart Poettering
11 <refentry id=
"systemd-volatile-root.service">
14 <title>systemd-volatile-root.service
</title>
15 <productname>systemd
</productname>
19 <contrib>Developer
</contrib>
20 <firstname>Lennart
</firstname>
21 <surname>Poettering
</surname>
22 <email>lennart@poettering.net
</email>
28 <refentrytitle>systemd-volatile-root.service
</refentrytitle>
29 <manvolnum>8</manvolnum>
33 <refname>systemd-volatile-root.service
</refname>
34 <refname>systemd-volatile-root
</refname>
35 <refpurpose>Make the root file system volatile
</refpurpose>
39 <para><filename>systemd-volatile-root.service
</filename></para>
40 <para><filename>/usr/lib/systemd/systemd-volatile-root
</filename></para>
44 <title>Description
</title>
46 <para><filename>systemd-volatile-root.service
</filename> is a service that replaces the root directory with a
47 volatile memory file system (
<literal>tmpfs
</literal>), mounting the original (non-volatile)
48 <filename>/usr
</filename> inside it read-only. This way, vendor data from
<filename>/usr
</filename> is available as
49 usual, but all configuration data in
<filename>/etc
</filename>, all state data in
<filename>/var
</filename> and all
50 other resources stored directly under the root directory are reset on boot and lost at shutdown, enabling fully
51 stateless systems.
</para>
53 <para>This service is only enabled if full volatile mode is selected, for example by specifying
54 <literal>systemd.volatile=yes
</literal> on the kernel command line. This service runs only in the initial RAM disk
55 (
"initrd"), before the system transitions to the host's root directory. Note that this service is not used if
56 <literal>systemd.volatile=state
</literal> is used, as in that mode the root directory is non-volatile.
</para>
60 <title>See Also
</title>
62 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
63 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
64 <citerefentry><refentrytitle>kernel-command-line
</refentrytitle><manvolnum>7</manvolnum></citerefentry>