IBM Support

PI80854: FURTHER IMPROVEMENT TO THE STAGING SPACE FREE SPACE MANAGEMENT LOGIC TO REDUCE THE CPU INCURRED FOR CERTAIN UR PROFILES

A fix is available

Subscribe

You can track all active APARs for this component.

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.  This is in addition to the improvements provided by
    APAR PI75970.
    

Local fix

  • No local fix is available
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Users who replicate large numbers of large   *
    *                 URs with a large mix of tables over a short  *
    *                 period of time.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: When the Staging Space is subjected to  *
    *                      a flow of a large number of table rows  *
    *                      of various sizes, the length of a chain *
    *                      of free areas can grow excessively. The *
    *                      logic that manages the chain of free    *
    *                      areas does not scale well for very      *
    *                      large numbers.  Excessive CPU is used   *
    *                      while the subscription appears to stall *
    *                      without sending any data to the target. *
    ****************************************************************
    * RECOMMENDATION: APPLY CORRECTIVE SERVICE                     *
    ****************************************************************
    
    When processing large numbers of varying sizes of row changes,
    the CPU use of the address space can rise excessively coupled
    with no data being sent to the target.
    

Problem conclusion

  • The method used to obtain free space for use has been changed
    to a best fit algorithm.  The method used to access the free
    chain has been changed from linear to logarithmic.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI80854

  • 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

    2017-05-01

  • Closed date

    2017-07-28

  • Last modified date

    2017-09-02

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

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

    UI49172

Modules/Macros

  •    CHCIISDL CHCMBARA CHCMBCHS CHCMBCHT CHCMBDAN
    CHCMBDES CHCMBDEU CHCMBELL CHCMBENG CHCMBENP CHCMBENU CHCMBESP
    CHCMBFIN CHCMBFRA CHCMBFRB CHCMBFRC CHCMBFRS CHCMBHEB CHCMBISL
    CHCMBITA CHCMBITS CHCMBJPN CHCMBKOR CHCMBNLB CHCMBNLD CHCMBNOR
    CHCMBPTB CHCMBPTG CHCMBRMS CHCMBRUS CHCMBSVE CHCMBTHA CHCMBTRK
    CHCMBZZZ CHCOSCIQ CHCSDTPF CHCSTGSP HCHCA21J
    

Fix information

  • Fixed component name

    INFO SRVR CDC Z

  • Fixed component ID

    5655U7600

Applicable component levels

  • RA21 PSY UI49172

       UP17/08/04 P F708

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 #: PI80854

Modified date: 02 September 2017


Translate this page: