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Cisco Bug: CSCvt39916 - Zookeeper out-of-sync situation during quick keepalived flaps

Last Modified

Oct 07, 2020

Products (1)

  • Cisco Ultra Services Framework

Known Affected Releases

USP_6.3.0

Description (partial)

Symptom:
Symptoms are varied. One possible symptom is the removal of functioning VMs from the system leading to potential service outages.

On the EMs, examination of the zookeeper logs under /var/log/em/zookeeper show a continuous stream of warning messages complaining that the accepted epoch is greater than the leader epoch.

Here is an example:

2020-02-18 08:43:26,900 [myid:51] - WARN  [QuorumPeer[myid=51]/192.168.46.51:2181:Follower@87] - Exception when following the leader
java.io.IOException: Leaders epoch, 6 is less than accepted epoch, 9
        at org.apache.zookeeper.server.quorum.Learner.registerWithLeader(Learner.java:293)
        at org.apache.zookeeper.server.quorum.Follower.followLeader(Follower.java:70)
        at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:846)

Conditions:
2 EM deployments where connectivity is impacted simultaneously on management and orchestration networks between the 2 EM instances.
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