Troubleshooting
Problem
Network Time Protocol (NTP) causes unexpected results with time-based software functions. Due to this behavior, IBM® does not support the use of NTP with WebSphere® Load Balancer.
Cause
Configuring NTP to use "slew" mode restricts the maximum allowed change in time. Ensure the time is not modified by more than to 0.1 seconds per update to minimize problems. Examples of Load Balancer time-related problems are high availability takeovers for no apparent problem, affinity unexpectedly broken, servers marked down by advisors when they are available, and possible forwarding errors.
Limiting the maximum time change reduces time-related problems in the Load Balancer, but does not eliminate problems. Automatic time updates such as NTP are not supported other than with "best effort" support. The only safe way to update the system clock without possible problems with the Load Balancer is to perform the time adjustments when the Load Balancer is not running.
Resolving The Problem
Disable NTP on the systems running the Load Balancer:
- For AIX™
"ntpdate" is used to control NTP functions. - For Linux™
The "ntpd" daemon is used and can be found and killed with "ps -ef|grep ntpd" then "kill ntpd_pid#". "ntpdate" and "chrony" are also time synchronization software available on linux systems that cause incorrect behavior with the Load Balancer. - For Microsoft™ Windows™
When the Load Balancer is installed on a Windows™ operating system, NTP or other software such as NetTime can automatically adjust the system clock.
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Document Information
Modified date:
26 December 2021
UID
swg21178386