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<?xml version="1.0"?>
<!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
SPDX-License-Identifier: LGPL-2.1+
This file is part of systemd.
Copyright 2016 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="systemd-volatile-root.service">
<refentryinfo>
<title>systemd-volatile-root.service</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-volatile-root.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-volatile-root.service</refname>
<refname>systemd-volatile-root</refname>
<refpurpose>Make the root file system volatile</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-volatile-root.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-volatile-root</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-volatile-root.service</filename> is a service that replaces the root directory with a
volatile memory file system (<literal>tmpfs</literal>), mounting the original (non-volatile)
<filename>/usr</filename> inside it read-only. This way, vendor data from <filename>/usr</filename> is available as
usual, but all configuration data in <filename>/etc</filename>, all state data in <filename>/var</filename> and all
other resources stored directly under the root directory are reset on boot and lost at shutdown, enabling fully
stateless systems.</para>
<para>This service is only enabled if full volatile mode is selected, for example by specifying
<literal>systemd.volatile=yes</literal> on the kernel command line. This service runs only in the initial RAM disk
("initrd"), before the system transitions to the host's root directory. Note that this service is not used if
<literal>systemd.volatile=state</literal> is used, as in that mode the root directory is non-volatile.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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