Hardware Clock having wrong time on cluster node

This document (7011375) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11 Service Pack 2
SUSE Linux Enterprise Server 11 Service Pack 1
SUSE Linux Enterprise High Availability Extension 11 Service Pack 2
 

Situation

The time of the hardware clock is wrong.
The server has been fenced and not shutdown in a normal way.

Resolution

In /etc/sysconfig/ntp there have been added 2 new parameters:
## Type:           boolean
## Default:        "no"
#
# Force time synchronization befor start ntpd
#
NTPD_FORCE_SYNC_ON_STARTUP="no"

## Type:           boolean
## Default:        "no"
#
# Force time synchronization of hwclock befor start ntpd
# This works only if NTPD_FORCE_SYNC_ON_STARTUP is set
# to yes.
#
NTPD_FORCE_SYNC_HWCLOCK_ON_STARTUP="no"


By default these are set to "no". When set to "yes", the time will be set to the hardware clock when ntpd starts.

Cause

Normally the hardware clock will be set to the time from ntpd when the server is restarted or shut down. In a cluster environment (NCS and HAE) often these servers are fenced and no normal shutdown happens. Due to this the hardware clock will not be set to the actual time.

In addition, the hardware clock will only be updated when the difference between hardware time  and Kernel is 15 minutes or less. In case of daylight saving time switch the difference is bigger and due to that the hardware clock will not be updated by the kernel itself.

Additional Information

Also in /etc/sysconfig/clock the following option has to be set to "yes" (default):
SYSTOHC="yes"

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7011375
  • Creation Date: 15-Nov-2012
  • Modified Date:16-Mar-2021
    • SUSE Linux Enterprise High Availability Extension
    • SUSE Linux Enterprise Server

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