Clock exception detected during RHEL7 Test

Clock exception detected during RHEL7 Test

Problem description:

About 24 hours will be slower than the standard time by 1 hour.

Analysis result:

After confirmation, the reason is that RHEL7 adopts chrony synchronization time. No longer use the previous ntp protocol, so how can I modify and configure the ntp service is invalid (Time drift constantly ).

Related Knowledge:

Chrony is two programs used to maintain the clock accuracy of computer systems. These two programs are named chronyd and chronyc.

Chronyd is a daemon running in the system background. It measures the offset of the local time based on other time server time on the network to adjust the system clock. For isolated systems, you can manually enter the correct time periodically (through chronyc ). In these two cases, chronyd determines the ratio of the computer speed, and correct it. Chronyd implements the NTP protocol and can be used as a server or client.

Chronyc is a user interface used to monitor chronyd performance and configure its parameters. It can control the chronyd processes running on the local machine and other computers.

Cause:

When testing the Hitachi Gateway project, an AD Domain Server was set up. The chrony service is automatically started when it is started by default. It is directly set to a unique time server after the Active Domain Server is searched.

Generally, the time between the virtual machine and the physical machine is inconsistent. This causes RHEL7 to adjust its hardware Time Offset based on the active domain time server, and the active domain to set its own system time based on the adjusted hardware time. Forms a vicious circle.

In the section about chrony in this document:

Solution:

Modify the configuration file of chronyd. The default file is/etc/chrony. conf.

The content of the/etc/chrony. keys file is:

YOUR_PASS

Start the chronyd program.

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