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IV14762: IMPROVE PERFORMANCE WHEN ROUND ROBIN AND SICK PATH EXISTS APPLIES TO AIX 7100-00

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APAR status

  • Closed as program error.

Error description

  • When running with timeout_policy set to fail_path or
disable_path, algorithm is set to round_robin, and health
check command is set to Test Unit Ready, there still
may be a severe I/O performance impact with one or more
paths are sick (going up and down) causing intermittent
command timeouts.

Even with this enhancement, there may still be periodic
I/O pauses unti the sick path is fixed or removed.

Local fix

  • 



Problem summary


    

  • When running with timeout_policy set to fail_path or
disable_path, algorithm is set to round_robin, and health
check command is set to Test Unit Ready, there still
may be a severe I/O performance impact with one or more
paths are sick (going up and down) causing intermittent
command timeouts.

Even with this enhancement, there may still be periodic
I/O pauses unti the sick path is fixed or removed.

    



Problem conclusion


    

  • AIX PCM will more aggressively degrade paths encountering
command timeouts, and keep them degraded longer.

    



Temporary fix


    

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IV14762
    • 

  • Reported component name
    AIX V7.1
    • 

  • Reported component ID
    5765H4000
    • 

  • Reported release
    710
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Submitted date
    2012-02-02
    • 

  • Closed date
    2012-02-02
    • 

  • Last modified date
    2013-02-26
    • 





    

  • APAR is sysrouted FROM one or more of the following:
    

    
IV08824
    

    • 

  • APAR is sysrouted TO one or more of the following:
    

    
U851531
    

    • 



Fix information


    

  • Fixed component name
    AIX V7.1
    • 

  • Fixed component ID
    5765H4000
    • 



Applicable component levels


    

  • R710  PSY  U851531
       UP12/04/02  I  1000
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            26 February 2013
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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