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Identity Engines - NTP Time Skew May Delay System Startup

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TitleIdentity Engines - NTP Time Skew May Delay System Startup
Symptoms
  • After Ignition server is rebooted, either RADIUS or Dashboard access may not be working.
  • After a variable period of time either RADIUS or Dashboard access starts working again without any user intervention.
Environment
  • Identity Engines
  • All Software Releases
  • High Availability (HA) or Standalone Deployments
  • NTP
Cause

NTP clock synchronization during the services restart phase of boot-up with a clock source at a point in the past compared to the Ignition VM.

Resolution
Starting with Ignition 9.5.0 NTP is now synchronized prior to the start of relevant system services to eliminate this condition.
 
For software releases prior to 9.5.0 Extreme recommends that Ignition virtual appliances retrieve their clock source from the host hypervisor (synchronize with hypervisor) and the hypervisors retrieve their clock source from NTP. This ensures a consistent clock provided by the hypervisors that will be in effect at startup of the Ignition appliance versus a clock that can be modified during Ignition startup by an unreliable external NTP clock source.
Additional notes

Ignition servers configured to use NTP (Network Time Protocol) for clock synchronization may experience unexpected delays in system restart or database synchronization.

When an Ignition server is restarted certain core system services can only be started if services they are dependent on have initialized. Such services may be subject to a holdback timer. The holdback timer is set based on the system clock in effect at the time; the holdback_time. If the NTP clock source it set to a point in the past and this synchronization occurs after the holdback_time is set, the affected service(s) will effectively wait until the system clock reaches the future holdback_time.

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