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IC71594: DB2LOGGR CHECKS FOR DYNAMIC REGISTRY DB2_DPS_LIMIT2 TOO OFTEN, MAY CAUSE PERFORMANCE ISSUES ON LARGE DPF INSTANCES.

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APAR status

  • Closed as program error.

Error description

  • An incredible amount of uncached registry reads was noticed from
    db2 traces - 1315 in 120 seconds, almost 10 times a second on
    each physical partition (8 MLNs). Uncached read means we are
    checking dynamic registry value, - we actually go to registry
    file on disk, lock it, read from it, unlock it. Since in DPF
    registry files are on NFS, this is too much overhead and too
    high of a price for using dynamic registries. Extrapolating to
    say for example 32 servers, - we attempt to read from global
    registry 320 times a second.
    
    This APAR fixes the issue of uncached registry reads.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * DB2 V9.5                                                     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * An incredible amount of uncached registry reads was          *
    * noticedfromdb2 traces - 1315 in 120 seconds, almost 10 times *
    * a secondoneach physical partition (8 MLNs). Uncached read    *
    * means we arechecking dynamic registry value, - we actually   *
    * go toregistryfile on disk, lock it, read from it, unlock it. *
    * Since in DPFregistry files are on NFS, this is too much      *
    * overhead and toohigh of a price for using dynamic            *
    * registries. Extrapolatingtosay for example 32 servers, - we  *
    * attempt to read from globalregistry 320 times a second.This  *
    * APAR fixes the issue of uncached registry reads.             *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 V9.5 FP7                                      *
    ****************************************************************
    

Problem conclusion

  • First fixed in DB2 V9.5 FP7
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC71594

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    950

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-09-30

  • Closed date

    2010-11-15

  • Last modified date

    2010-11-15

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

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

    IC75157

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R950 PSY

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.5

Reference #: IC71594

Modified date: 15 November 2010