Help with isolated node scenario

[Valeriano Tortola]

Hi,

I do not fully understand what happens when a node gets partitioned and it is not accessible for a while

• Consider nodes A, B, C. 
  
• A is the current leader of term 1.
  
• Because a network issue, C is not reachable anymore.
  
• A and B will continue working normally since they are majority.
  
• However C cannot reach or be reached by anybody, so he starts its own election incrementing term to 2.
  
• Network conditions are restored and C connects to the cluster again.
  
• However C is rejecting A AppendEntries requests, since they indicate term 1 and his is 2 ( restriction 5.1)
  
• C starts an election for term 3, but nobody votes him because its log is outdated.
  
• C never gets to either become leader or follow the others.
  

It seems I have missed something, how would C join the other 3 and accepts entries from A?

Thanks.

[Martin Hedenfalk]

C's rejection of A's AppendEntries request includes term=2, which causes A to step down.

    .martin

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[Valeriano Tortola]

Then A would step down and start a new election? Because cannot just become follower of a node that has not all the committed entries.

Thanks!

[Martin Hedenfalk]

A steps down when it sees C's higher term 2, and updates it's current term to 2. Then there will be normal elections in term 3 and above.

[Valeriano Tortola]

Apologies for the delay and thanks!.