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LI73100: INTERNAL RESOURCE CONTENTION DURING PARALLEL ONLINE BACKUP MAY LEAD TO LESS THAN OPTIMAL THROUGHPUT

Fixes are available

DB2 Version 9.1 Fix Pack 7  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 7a  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 8  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 9  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 10  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 11  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 12  for Linux, UNIX and Windows

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • When performing an online parallel backup, the I/O activity will
be done by the prefetcher processes.
In the current algorithm, these can be seen as competing for the
same resource when examining repeated stack traces of these
processes during a backup process.

A typical stack exposing this contention would show :

   getConflictComplex__17SQLO_SLATCH_CAS64FCUl + 0x244
   getConflict__17SQLO_SLATCH_CAS64FCUl + 0xE0

@28@3@sqloltch_track__FCP10sqlo_latchCUlCPCcT2C14SQLO_LT_VALUES
- 0x58
   sqlbLatchPoolRange__FP12SQLB_GLOBALSUsUiT3PiT5ib + 0x334
   sqlbDMSDirectRead__FP17SQLB_DIRECT_IO_CB + 0x14
   sqlbDirectRead__FP17SQLB_DIRECT_IO_CB - 0x6C
   sqlbServiceDirectReadRequest__FP11SQLB_pfMisc + 0x6BC
   sqlbPFPrefetcherEntryPoint__FPcUi + 0x444

This apar reduces the resource latching needed and should hence
improve throughput during the online backup.

The impact of this problem depends on the speed of the backup
media
( this is the bottleneck in most cases ). The speed of the
offline backup with the same parameters is a reasonable measure
of the fastest throughput that can be achieved, but online will
always carry more overhead.

Local fix

  • n/a

Problem summary

  • Problem summary : suboptimal online backup performance due to
internal latching contention
Users Affected : all ( parallel ) online backup users
Problem conclusion : this apar improves online backup
performance

Problem conclusion

  • This problem was first fixed in v9.1 fixpak 7.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    LI73100
    • 

  • Reported component name
    DB2 UDE ESE LIN
    • 

  • Reported component ID
    5765F4104
    • 

  • Reported release
    910
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2008-01-30
    • 

  • Closed date
    2009-04-28
    • 

  • Last modified date
    2009-04-28
    • 





    

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

    • 

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

    
LI73105
    

    • 



Fix information


    

  • Fixed component name
    DB2 UDE ESE LIN
    • 

  • Fixed component ID
    5765F4104
    • 



Applicable component levels


    

  • R910  PSN
       UP
    • 

  • R950  PSN
       UP
    • 








      
              
                            

              

              [{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"910","Line of Business":{"code":"LOB10","label":"Data and AI"}}]
              

                          

          
 
        

      

    

      

        

          

            
Document Information


            

            


                        

            Modified date:
            

            15 October 2021
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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