How Leap Second Affects The OS Clock on Linux and Oracle VM
(Doc ID 1453523.1)
Last updated on MAY 11, 2023
Applies to:
Oracle VM - Version 2.1 and laterLinux OS - Version Oracle Linux 4.8 and later
Oracle WebCenter Content - Version 11.1.1.6.0 to 11.1.1.6.0 [Release 11g]
Oracle Cloud Infrastructure - Version N/A and later
Linux x86
Linux x86-64
Purpose
This document describes what the leap second is, and how it affects to the OS clock on Linux and Oracle VM. Linux OS works fine even with the leap second(if there are no bugs), however applications on the OS may be affected especially when the OS clock is backward adjusted. Please contact application vendors to clarify whether the application is affected by the leap second.
In general, the OS clock which has the leap second is:
time environment
Arch | without ntpd | with ntpd(with default zoneinfo) | ||||
---|---|---|---|---|---|---|
with old/default zoneinfo | with right zoneinfo | ntpd >= 4.2.2p1-9 | ntpd < 4.2.2p1-9 | |||
leap=01 | leap=10 | |||||
Physical (baremetal) Server | OL4/OL5/OL6/UEK1/UEK2 x86/x86_64 |
not adjusted (differs 1sec, not backward) | adjusted as per leap second (with out backward, but with inserting ##:##:60 or removing ##:##:59) | adjusted gradually taking for a long time (not backward) | adjusted with 1 sec backward | adjusted with skipping 1 sec (not backward) |
Xen or Oracle VM | Dom0 | paused for 1 sec immediately before leap second (not backward) | ||||
DomU(PVM) Linux PVM kernel(kernel-xen) | ||||||
DomU(HVM) | depend on HVM kernel |
Details
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In this Document
Purpose |
Details |
What is the "leap second"? |
What might be a problem with leap second? |
How about Linux without ntp? |
How about Linux with ntp? |
How about other Operating Systems? |
References |