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  1. Couchbase Documentation
  2. DOC-10874

Clarify what node re-initialization means after doing "unsafe mode" fail over



    • Improvement
    • Resolution: Unresolved
    • Major
    • None
    • 7.1, 7.1.3, 7.2
    • docs-site
    • None
    • 0



      With 7.0+ comes "unsafe mode" fail over. 
      It is mentionned inside our documentation:



      In order that users do not have to abandon a cluster in which a majority of nodes have failed or are unreachable, hard failover can be performed in unsafe mode. Unsafe failovers override the consensus protocol; and may be performed even if a majority of nodes in the cluster cannot be contacted. No unsafe failover should be attempted without a full understanding of the consequences and requirements, which are listed immediately below. 





      As described above, in Consequences of Unsafe Failover, following unsafe failover, the failed-over nodes cannot be recovered; and will need to be entirely re-initialized, in order to be re-introduced into the cluster. 




      The consequences of unsafe failover in Couchbase Server Version 7.0+ are therefore significantly different from in previous versions: previously, the failed over nodes remained in the cluster, and could be recovered; but in 7.0+, they are removed from the cluster, are non-recoverable, and must be re-initialized before being added back to the cluster. 


      QUESTION: what do we mean EXACTLY saying following unsafe mode fail over, "failed over nodes must be re-initialized before being added back to the cluster" ?


      Should the nodes be completely uninstall and re install?

      I ask this question because I tested:

      • doing nothing (just adding the node back) => NOT OK => the node thinks it is part of the cluster and see other nodes in orange/red state (see attachement my_tests.docx for all detailed tests containing screen capture)
      • doing a 

        couchbase-cli node-init

        same result => NOT OK => no change compared to previous attempts after node is re introduced.

      So I think it means uninstall + re install node but would like confirmation.
      Can anybody  confirm?




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            gary.gray Gary Gray
            fabrice.leray Fabrice Leray
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