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  1. Couchbase Server
  2. MB-54679

Max count auto failover: inconsistency between new (7.1+) auto failover server group pre requisites and durability needs

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Details

    • Bug
    • Resolution: Duplicate
    • Major
    • 7.2.0
    • 7.1.4, 7.1.0, 7.1.1, 7.1.2, 7.1.3
    • ns_server
    • Untriaged
    • 0
    • Unknown
    • High

    Description

      All thread details in https://couchbase.slack.com/archives/CFKS0KP38/p1668699568433149

      Starting with 7.1+, auto failover server group policy has changed a lot:
      See https://docs.couchbase.com/server/current/learn/clusters-and-availability/groups.html#understanding-server-group-awareness, especially:

      A server group can be automatically failed over: thus, if the entire group goes offline, and active vBuckets and indexes are thereby inaccessible, the replica vBuckets and replica indexes that remain available on another group can be automatically promoted to active status. In 7.1+, this is achieved by setting the maximum count for auto-failover to a value equal to or greater than the number of nodes in the server group. See Automatic Failover.
      And also (same thing but said differently) :
      https://docs.couchbase.com/server/current/learn/clusters-and-availability/groups.html#defining-groups-and-enabling-group-failover

      Note that in 7.1+, automatic failover can fail over more than three nodes concurrently: this has permitted the deprecation of pre-7.1 interfaces that were specific to triggering auto-failover for server groups. Consequently, in order to ensure successful auto-failover of a server group, the maximum count for auto-failover must be established by the administrator as a value equal to or greater than the number of nodes in the server group. See Automatic Failover.
      QUESTION: Does it mean there is a conflict between durability requirement (where max number of sequential automatic failover MUST be max=1 see https://docs.couchbase.com/server/current/learn/data/durability.html#protection-guarantees-2-replicas, same condition applies with 1 replica) and the fact to have server group enabled (where we would need to set “a value equal to or greater than the number of nodes in the server group” _ which means of course more than 1...)?Shortly said, does it mean we cannot have _both durability AND server group auto failover in 7.1.+?

       

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              pulkit.matta Pulkit Matta
              fabrice.leray Fabrice Leray
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