openstack-manuals/doc/install-guide/section_basics-ntp.xml

<?xml version="1.0" encoding="UTF-8"?>
<section xmlns="http://docbook.org/ns/docbook"
  xmlns:xi="http://www.w3.org/2001/XInclude"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  version="5.0"
  xml:id="basics-ntp">
  <?dbhtml stop-chunking?>
  <title>Network Time Protocol (NTP)</title>
  <para>You must install
    <glossterm baseform="Network Time Protocol (NTP)">NTP</glossterm> to
    properly synchronize services among nodes. We recommend that you configure
    the controller node to reference more accurate (lower stratum) servers and
    other nodes to reference the controller node.</para>
  <section xml:id="basics-ntp-controller-node">
    <title>Controller node</title>
    <procedure>
      <title>To install the NTP service</title>
      <step>
        <screen os="ubuntu;debian"><prompt>#</prompt> <userinput>apt-get install ntp</userinput></screen>
        <screen os="rhel;fedora;centos"><prompt>#</prompt> <userinput>yum install ntp</userinput></screen>
        <screen os="opensuse;sles"><prompt>#</prompt> <userinput>zypper install ntp</userinput></screen>
      </step>
    </procedure>
    <procedure>
      <title>To configure the NTP service</title>
      <para>By default, the controller node synchronizes the time via a pool
        of public servers. However, you can optionally edit the
        <filename>/etc/ntp.conf</filename> file to configure alternative
        servers such as those provided by your organization.</para>
      <step>
        <para>Edit the <filename>/etc/ntp.conf</filename> file and add,
          change, or remove the following keys as necessary for your
          environment:</para>
        <programlisting language="ini">server <replaceable>NTP_SERVER</replaceable> iburst
restrict -4 default kod notrap nomodify
restrict -6 default kod notrap nomodify</programlisting>
        <para>Replace <replaceable>NTP_SERVER</replaceable> with the
          hostname or IP address of a suitable more accurate (lower stratum)
          NTP server. The configuration supports multiple
          <literal>server</literal> keys.</para>
        <note>
          <para>For the <literal>restrict</literal> keys, you essentially
            remove the <literal>nopeer</literal> and <literal>noquery</literal>
            options.</para>
        </note>
        <note os="ubuntu;debian">
          <para>Remove the <filename>/var/lib/ntp/ntp.conf.dhcp</filename> file
            if it exists.</para>
        </note>
      </step>
      <step os="ubuntu;debian">
        <para>Restart the NTP service:</para>
        <screen><prompt>#</prompt> <userinput>service ntp restart</userinput></screen>
      </step>
      <step os="rhel;centos;fedora;sles;opensuse">
        <para>Start the NTP service and configure it to start when the system
          boots:</para>
        <screen os="rhel;centos;fedora"><prompt>#</prompt> <userinput>systemctl enable ntpd.service</userinput>
<prompt>#</prompt> <userinput>systemctl start ntpd.service</userinput></screen>
        <para os="sles">On SLES:</para>
        <screen os="sles"><prompt>#</prompt> <userinput>service ntp start</userinput>
<prompt>#</prompt> <userinput>chkconfig ntp on</userinput></screen>
        <para os="opensuse">On openSUSE:</para>
        <screen os="opensuse"><prompt>#</prompt> <userinput>systemctl enable ntp.service</userinput>
<prompt>#</prompt> <userinput>systemctl start ntp.service</userinput></screen>
      </step>
    </procedure>
  </section>
  <section xml:id="basics-ntp-other-nodes">
    <title>Other nodes</title>
    <procedure>
      <title>To install the NTP service</title>
      <step>
        <screen os="ubuntu;debian"><prompt>#</prompt> <userinput>apt-get install ntp</userinput></screen>
        <screen os="rhel;fedora;centos"><prompt>#</prompt> <userinput>yum install ntp</userinput></screen>
        <screen os="opensuse;sles"><prompt>#</prompt> <userinput>zypper install ntp</userinput></screen>
      </step>
    </procedure>
    <procedure>
      <title>To configure the NTP service</title>
      <para>Configure the network and compute nodes to reference the
        controller node.</para>
      <step>
        <para>Edit the <filename>/etc/ntp.conf</filename> file:</para>
        <para>Comment out or remove all but one <literal>server</literal>
          key and change it to reference the controller node.</para>
        <programlisting language="ini">server <replaceable>controller</replaceable> iburst</programlisting>
        <note os="ubuntu;debian">
          <para>Remove the <filename>/var/lib/ntp/ntp.conf.dhcp</filename> file
            if it exists.</para>
        </note>
      </step>
      <step os="ubuntu;debian">
        <para>Restart the NTP service:</para>
        <screen><prompt>#</prompt> <userinput>service ntp restart</userinput></screen>
      </step>
      <step os="rhel;centos;fedora;sles;opensuse">
        <para>Start the NTP service and configure it to start when the system
          boots:</para>
        <screen os="rhel;fedora;centos"><prompt>#</prompt> <userinput>systemctl enable ntpd.service</userinput>
<prompt>#</prompt> <userinput>systemctl start ntpd.service</userinput></screen>
        <para os="sles">On SLES:</para>
        <screen os="sles"><prompt>#</prompt> <userinput>service ntp start</userinput>
<prompt>#</prompt> <userinput>chkconfig ntp on</userinput></screen>
        <para os="opensuse">On openSUSE:</para>
        <screen os="opensuse"><prompt>#</prompt> <userinput>systemctl enable ntp.service</userinput>
<prompt>#</prompt> <userinput>systemctl start ntp.service</userinput></screen>
      </step>
    </procedure>
  </section>
  <section xml:id="basics-ntp-verify">
    <title>Verify operation</title>
    <para>We recommend that you verify NTP synchronization before proceeding
      further. Some nodes, particularly those that reference the controller
      node, can take several minutes to synchronize.</para>
    <procedure>
      <step>
        <para>Run this command on the <emphasis>controller</emphasis> node:
        </para>
        <screen><prompt>#</prompt> <userinput>ntpq -c peers</userinput>
<computeroutput>     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*ntp-server1     192.0.2.11       2 u  169 1024  377    1.901   -0.611   5.483
+ntp-server2     192.0.2.12       2 u  887 1024  377    0.922   -0.246   2.864</computeroutput></screen>
        <para>Contents in the <emphasis>remote</emphasis> column should
          indicate the hostname or IP address of one or more NTP servers.</para>
        <note>
          <para>Contents in the <emphasis>refid</emphasis> column typically
            reference IP addresses of upstream servers.</para>
        </note>
      </step>
      <step>
        <para>Run this command on the <emphasis>controller</emphasis> node:
        </para>
        <screen><prompt>#</prompt> <userinput>ntpq -c assoc</userinput>
<computeroutput>ind assid status  conf reach auth condition  last_event cnt
===========================================================
  1 20487  961a   yes   yes  none  sys.peer    sys_peer  1
  2 20488  941a   yes   yes  none candidate    sys_peer  1</computeroutput></screen>
        <para>Contents in the <emphasis>condition</emphasis> column should
          indicate <literal>sys.peer</literal> for at least one server.</para>
      </step>
      <step>
        <para>Run this command on <emphasis>all other</emphasis> nodes:</para>
        <screen><prompt>#</prompt> <userinput>ntpq -c peers</userinput>
<computeroutput>     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*controller      192.0.2.21       3 u   47   64   37    0.308   -0.251   0.079</computeroutput></screen>
        <para>Contents in the <emphasis>remote</emphasis> column should
          indicate the hostname of the controller node.</para>
        <note>
          <para>Contents in the <emphasis>refid</emphasis> column typically
            reference IP addresses of upstream servers.</para>
        </note>
      </step>
      <step>
        <para>Run this command on <emphasis>all other</emphasis> nodes:
        </para>
        <screen><prompt>#</prompt> <userinput>ntpq -c assoc</userinput>
<computeroutput>ind assid status  conf reach auth condition  last_event cnt
===========================================================
  1 21181  963a   yes   yes  none  sys.peer    sys_peer  3</computeroutput></screen>
        <para>Contents in the <emphasis>condition</emphasis> column should
          indicate <literal>sys.peer</literal>.</para>
      </step>
    </procedure>
  </section>
</section>