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VM65180: HPF COULD BE ERRONEOUSLY TURNED OFF FOR CHPIDV GUESTS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • If CP system initialization happens to determine that the
    lowest max data count of all FICON channels in the system
    is X'FFFF' (max value), then it will erroneously set the
    system max data count value to 0 for CHPIDV guests in
    affect shutting off HPF for CHPIDV guests.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All z/VM users of High Performance FICON     *
    *                 channels (zHPF) and CHPIDV guests            *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    ****************************************************************
    * RECOMMENDATION: APPLY PTF                                    *
    ****************************************************************
    During CP system initialization FICON channels associated with
    D/T2107 DS8000 DS8800 control units are tested to see if they
    are High Performance FICON channels.  A maximum data count
    (MAXD) value is associated with FICON HPF channels.  CP keeps
    track of the lowest MAXD value of all FICON channels on the
    system (if a FICON channel is found that doesn't support HPF
    then the system MAXD value is zero).  This value is used by CP
    to indicate to CHPIDV guests on the system what max data count
    value is supported on the system for them.  This value starts
    at X'FFFF' and is lowered during system initialization anytime
    a lower MAXD value is discovered.  If the MAXD value remains
    at X'FFFF' then it is assumed by CP that no control units were
    found that supports HPF, so the value is reset to X'0000'.
    However, X'FFFF' could be a valid value for MAXD, so CP should
    not reset the value to zero since this could be erroneous.
    

Problem conclusion

  • Instead of depending on a MAXD value of X'FFFF' to determine
    if an HPF capable control unit was found, CP now will use
    a flag in the SYSCM, SYSMAXDV, to indicate this.  If the
    flag is on, then the MAXD count (SYSMAXD) is valid.  If the
    flag is off, then SYSMAXD is reset to X'0000' to indicate that
    HPF is not supported on the system for CHPIDV guests.
    

Temporary fix

  • FOR RELEASE VM/ESA CP/ESA R620 :
    PREREQ: VM65041 VM65042
    CO-REQ: NONE
    IF-REQ: NONE
    

Comments

APAR Information

  • APAR number

    VM65180

  • Reported component name

    VM CP

  • Reported component ID

    568411202

  • Reported release

    620

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-05-23

  • Closed date

    2012-06-06

  • Last modified date

    2012-11-20

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

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

    UM33724

Modules/Macros

  • HCPIIO   HCPSYSCM HCPZCP
    

Fix information

  • Fixed component name

    VM CP

  • Fixed component ID

    568411202

Applicable component levels

  • R620 PSY UM33724

       UP12/06/07 P 1202

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: z/VM family

Software version: 620

Operating system(s): z/VM

Reference #: VM65180

Modified date: 20 November 2012


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