Enabling chrony or ntpd for Red Hat 7/CentOS 7 Systems

Before you can install Vertica, you must enable one of the following on your system for clock synchronization:

You must enable and activate the Network Time Protocol (NTP) before installation. Otherwise, the installer reports this issue with the identifier S0030.

For information on installing and using chrony, see the information below. For information on NTPD see Enabling Network Time Protocol (NTP).

Install chrony

The chrony suite consists of:

chrony is installed by default on some versions of Red Hat/CentOS 7. However, if chrony is not installed on your system, you must download it. To download chrony, run the following command as sudo or root:

# yum install chrony

Verify That chrony Is Running

To view the status of the chronyd daemon, run the following command:

$ systemctl status chronyd

If chrony is running, an output similar to the following appears:

chronyd.service - NTP client/server
    Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled)
    Active: active (running) since Mon 2015-07-06 16:29:54 EDT; 15s ago
Main PID: 2530 (chronyd)
    CGroup: /system.slice/chronyd.service
            ââ2530 /usr/sbin/chronyd -u chrony

If chrony is not running, execute the following command as sudo or root. This command also causes chrony to run at boot time:

# systemctl enable chronyd

Verify That chrony Is Operating Correctly

To verify that the chrony daemon is operating correctly, issue the following command on all nodes in the cluster:

$ chronyc tracking

An output similar to the following appears:

Reference ID    : (time01.website.org)
Stratum         : 3
Ref time (UTC)  : Thu Jul  9 14:58:01 2015
System time     : 0.000035685 seconds slow of NTP time
Last offset     : -0.000151098 seconds
RMS offset      : 0.000279871 seconds
Frequency       : 2.085 ppm slow
Residual freq   : -0.013 ppm
Skew            : 0.185 ppm
Root delay      : 0.042370 seconds
Root dispersion : 0.022658 seconds
Update interval : 1031.0 seconds
Leap status     : Normal

A stratum level of 16 indicates that chrony is not synchronizing correctly. If chrony continues to detect a stratum level of 16, verify that the UDP port 323 is open. This port must be open on all firewalls between the cluster and the remote machine to which you are attempting to synchronize.

Red Hat Documentation Related to chrony

These links to Red Hat documentation were current as of the last publication of the Vertica documentation. Be aware that they could change between releases: