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PI75970: REQUESTED IMPROVEMENT TO STAGING SPACE FREE SPACE MANAGEMENT LOGIC TO REDUCE CPU FOR CERTAIN UR PROFILES

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Certain mixes of logged URs can produce the condition of a very
    long free chain of very small elements in the Staging Space.
    This will cause attempts to obtain free storage for a new row
    image to take significantly longer and use elevated levels of
    CPU.  This can delay replication to the point where it appears
    to stall.  An enhancement to the management of free space is
    required.
    

Local fix

  • No local fix is available.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Users of IIDR CDC for z/OS who generate very *
    *                 large URs containing data to be replicated   *
    *                 in the DB2 Log.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: The method of handling fragmented free  *
    *                      storage for the Storage Space resource  *
    *                      becomes very inefficient when the       *
    *                      number of elements on the free space    *
    *                      chain becomes high.                     *
    ****************************************************************
    * RECOMMENDATION: APPLY CORRECTIVE SERVICE                     *
    ****************************************************************
    
    The algorithm for managing free space in the Staging Space needs
    to be made more efficient.
    

Problem conclusion

  • The algorithm has been improved by reducing the number of times
    that free space management accesses storage above the bar when
    looking for a suitably sized segment of free space.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI75970

  • Reported component name

    INFO SRVR CDC Z

  • Reported component ID

    5655U7600

  • Reported release

    A21

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-02-06

  • Closed date

    2017-05-01

  • Last modified date

    2017-06-02

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

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

    UI46865

Modules/Macros

  •    CHCCDASW CHCSTGSP HCHCA21J
    

Fix information

  • Fixed component name

    INFO SRVR CDC Z

  • Fixed component ID

    5655U7600

Applicable component levels

  • RA21 PSY UI46865

       UP17/05/17 P F705

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



Document information

More support for: InfoSphere Data Replication for DB2 for z/OS

Software version: 10.2.1

Reference #: PI75970

Modified date: 02 June 2017


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