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IV97148: CAA:SLOW GOSSIP RECEIPT ON BOOT MAY CAUSE PARTITIONED CLUSTER

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APAR status

  • Closed as program error.

Error description

  • **************************************************************
* USERS AFFECTED:
* Systems running the AIX 6100-09 Technology Level
* or VIOS 2.2.x.x
* with bos.cluster.rte at the 6.1.9.200 or 6.1.9.201 level.
  **************************************************************
* ERROR DESCRIPTION:
* After rebooting a node in either a PowerHA or VIOS SSP
* cluster
* using CAA, there is a chance that the node may create its own
* cluster, causing a split-brain / partitioned cluster in the
* CAA environment.
*
* This is more likely to be seen if the network is slow and
* there is a delay in gossip packets being received by the
* rebooted node.
*
* The effect of a split-brain / partitioned cluster can vary,
* but in the worst cases: PowerHA may react by bringing
* resources online at the same time on multiple nodes, and
* VIOS SSP can experience pool going down on one or more nodes.
  **************************************************************
* RECOMMENDATION:
* Install APAR IV97148.
* Prior to fix availability, an interim fix is available from
* either
* ftp://aix.software.ibm.com/aix/ifixes/iv97148/
* https://aix.software.ibm.com/aix/ifixes/iv97148/
* Installation of the ifix requires a reboot.
  **************************************************************

Local fix

  • n/a

Problem summary

  • PROBLEM SUMMARY:
After rebooting a node in either a PowerHA or VIOS SSP
cluster using CAA, there is a chance that the node may
create its own cluster, causing a split-brain / partitioned
cluster in the CAA environment.
This is more likely to be seen if the network is slow and
there is a delay in gossip packets being received by the
rebooted node.
The effect of a split-brain / partitioned cluster can vary,
but in the worst cases: PowerHA may react by bringing
resources online at the same time on multiple nodes, and
VIOS SSP can experience pool going down on one or more
nodes.

Problem conclusion

  • There is a gate in which all initial clusterwide lock
requests should consider the count of nodes heartbeating to
the repository in addition to those gossiping over network.
There was a hole in the gate and the fix closes it.

Temporary fix

  •   *********
  * HIPER *
  *********

Comments

  • 



APAR Information




    

  • APAR number
    IV97148
    • 

  • Reported component name
    AIX 610 STD EDI
    • 

  • Reported component ID
    5765G6200
    • 

  • Reported release
    610
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    YesHIPER
    • 

  • Submitted date
    2017-06-12
    • 

  • Closed date
    2017-06-13
    • 

  • Last modified date
    2017-11-07
    • 






Fix information


    

  • Fixed component name
    AIX 610 STD EDI
    • 

  • Fixed component ID
    5765G6200
    • 



Applicable component levels


    

  • R610  PSY  U870060
       UP17/10/17  I  1000
    • 



PTF to Fileset Mapping








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            17 December 2021
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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