Clock skew problems between nodes on an IBM x3850 M2 system

Solution Unverified - Updated -

Issue

  • Kernel picks the TSC as a clock source on two-node x3850 M2 system causing a noticeable clock skew.
  • Following messages from ntp are seen in the logs :
June  8 17:51:42 hostname ntpd[5658]: frequency error 776 PPM exceeds tolerance 500 PPM
June  8 17:52:32 hostname ntpd[5658]: synchronized to 10.94.59.92, stratum 1
June  8 17:52:32 hostname ntpd[5658]: frequency error 776 PPM exceeds tolerance 500 PPM
June  8 17:53:01 hostname ntpd[5658]: no servers reachable
June  8 17:53:38 hostname ntpd[5658]: synchronized to 10.94.59.91, stratum 1
June  8 17:53:38 hostname ntpd[5658]: frequency error 777 PPM exceeds tolerance 500 PPM
June  8 17:53:39 hostname ntpd[5658]: frequency error 638 PPM exceeds tolerance 500 PPM
June  8 17:55:35 hostname ntpd[5658]: frequency error 517 PPM exceeds tolerance 500 PPM
June  8 17:55:52 hostname ntpd[5658]: no servers reachable
June  8 17:57:14 hostname ntpd[5658]: synchronized to 10.94.59.91, stratum 1
June  8 17:57:14 hostname ntpd[5658]: frequency error 777 PPM exceeds tolerance 500 PPM
June  8 17:57:15 hostname ntpd[5658]: frequency error 569 PPM exceeds tolerance 500 PPM

Environment

  • Red Hat Enterprise Linux 5.6, 5.7
  • IBM x3850 M2

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