NTP leap second event causing Oracle Clusterware node reboot
(Doc ID 759143.1)
Last updated on JUNE 05, 2019
Applies to:Oracle Database - Enterprise Edition - Version 10.1.0.2 to 220.127.116.11 [Release 10.1 to 12.1]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
UTC time (Coordinated Universal Time) is regularly adjusted by introducing a leap second based on the accumulated difference between the atomic clock time (TAI) and UT1, the time reflecting the Earth's rotational speed.
The decision to introduce a leap second in UTC is the responsibility of the Earth Orientation Center of the International Earth Rotation and reference System Service (IERS).
Due to the backwards time setting, NTP daemons have to adjust the time in accordance to the leap second requirement, which may affect certain versions of Oracle Clusterware to the degree that unforeseen node reboots may occur.
Leap second adjustments may affect any cluster configuration that depends on time accuracy on a per node or cluster basis, typically established by using NTP for time synchronization.
Oracle Clusterware supports two different deployments; one in which Oracle Clusterware is used as a standalone cluster solution on the system and another one in which Oracle Clusterware is used in combination with a certified third party cluster solution.
If Oracle Clusterware is used in combination with a certified third party cluster solution on your system, this note does not apply to you, as the certified third party cluster solution will handle the necessary leap second adjustments.
You should consult with your third party cluster solution provider to verify whether your cluster solution is affected by automatic leap second adjustments. For Oracle Solaris Cluster, leap second adjustments are handled automatically.
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