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  1. Apache Ozone
  2. HDDS-3698 Ozone Non-Rolling upgrades
  3. HDDS-4342

Add DataNode state and transitions for a node going through upgrade



    • Sub-task
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • None
    • None
    • None


      A typical SCM sequence for driving datanodes through upgrade would be

      Something like following :                                                                  

      • client sends Finalize                                                      
      • SCM moves to Finalizing states. If SCM crashes, and it comes up            

         it will always restart from this state.                                    

      • SCM disallows new pipeline creation, SCM in safe mode                      

          (SCM Freeze for new pipeline)                                             

      • SCM closes existing pieplines                                              
      • SCM updates MLV = SLV if not already so. Update on-disk MLV state.         
      • SCM moves all data nodes to HEALTHY_READONLY state. Please note that       

         initial state for all data node is HEALTHY_READONLY. For data nodes        

         to move from HEALTHY_READONLY -> HEALTHY, they need to send atleast        

         one heartbeat where DN.MLV == SCM.MLV                                      

      • SCM waits for few heartbeats                                               
      • SCM allows new pipeline creation (SCM thaw for new pipeline creation).     

         New Pipelines can be created if enough HEALTHY data nodes are found.       

      • If SCM comes across any data node heart beat with DN.MLV < SCM.MLV => SCM sends

         that data node finalize command 



      As part of this, we would be introducing a new state HEALTHY-READONLY in DataNode state machine maintained in SCM .

      This Jira will be used to make changes in the datanode state machine.                                                    


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              ppogde Prashant Pogde
              ppogde Prashant Pogde
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