+ <refsect1>
+ <title>Journal Namespaces</title>
+
+ <para>Journal 'namespaces' are both a mechanism for logically isolating the log stream of projects
+ consisting of one or more services from the rest of the system and a mechanism for improving
+ performance. Multiple journal namespaces may exist simultaneously, each defining its own, independent log
+ stream managed by its own instance of <command>systemd-journald</command>. Namespaces are independent of
+ each other, both in the data store and in the IPC interface. By default only a single 'default' namespace
+ exists, managed by <filename>systemd-journald.service</filename> (and its associated socket
+ units). Additional namespaces are created by starting an instance of the
+ <filename>systemd-journald@.service</filename> service template. The instance name is the namespace
+ identifier, which is a short string used for referencing the journal namespace. Service units may be
+ assigned to a specific journal namespace through the <varname>LogNamespace=</varname> unit file setting,
+ see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
+ details. The <option>--namespace=</option> switch of
+ <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> may be
+ used to view the log stream of a specific namespace. If the switch is not used the log stream of the
+ default namespace is shown, i.e. log data from other namespaces is not visible.</para>
+
+ <para>Services associated with a specific log namespace may log via syslog, the native logging protocol
+ of the journal and via stdout/stderr; the logging from all three transports is associated with the
+ namespace.</para>
+
+ <para>By default only the default namespace will collect kernel and audit log messages.</para>
+
+ <para>The <command>systemd-journald</command> instance of the default namespace is configured through
+ <filename>/etc/systemd/journald.conf</filename> (see below), while the other instances are configured
+ through <filename>/etc/systemd/journald@<replaceable>NAMESPACE</replaceable>.conf</filename>. The journal
+ log data for the default namespace is placed in
+ <filename>/var/log/journal/<replaceable>MACHINE_ID</replaceable></filename> (see below) while the data
+ for the other namespaces is located in
+ <filename>/var/log/journal/<replaceable>MACHINE_ID</replaceable>.<replaceable>NAMESPACE</replaceable></filename>.</para>
+ </refsect1>
+