[GitHub] [ozone] neils-dev commented on pull request #3409: HDDS-6743. Specify leader node for OM failover

["neils-dev (via GitHub)" <gi...@apache.org>]

neils-dev commented on PR #3409:
URL: https://github.com/apache/ozone/pull/3409#issuecomment-1428986721

   Thanks @symious .  I tested failover on the docker ha dev cluster and noticed that when leader node goes down, the followers respond in one of two ways, either i.) initially providing a stale om leader or ii,) null address om suggestion.
   
   i.) (stale leader suggestion) `ozone-ha-om2-1  | 2023-02-14 01:22:51 DEBUG OzoneManagerProtocolServerSideTranslatorPB:251 - OM:om2 is not the leader. Suggested leader is OM:om3[om3/172.27.0.9].`
   
   ii.) `ozone-ha-om2-1  | 2023-02-14 01:24:07 DEBUG OzoneManagerProtocolServerSideTranslatorPB:251 - OM:om2 is not the leader. Suggested leader is OM:om3[null].`
   
   
   The null address in the suggestion seems to be effective causing the failover provider to choose the next om to try from its om node map and resolves the failover.
   
   
   Q. should the node give a stale om leader id, is it possible that we encounter a loop condition where we continue to try the suggestion, fail, then ask the same om for the suggestion that we already tried?
   https://github.com/symious/ozone/blob/98caa74e8870829f974e77b89da6d293b7db62cd/hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/ha/OMFailoverProxyProviderBase.java#L189


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