OA41355: IST1222I INOP FOR MPC SUBCHANNEL WHEN VTAM ON THE OTHER SIDE OF ACTIVE MPC IS STOPPED AND RE-STARTED.

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APAR status

  • Closed as program error.

Error description

  • IST1222I INOP for MPC subchannel when VTAM on the other side
    of active MPC is stopped and re-started.
    The MPC itself re-activates - because other read and write
    subchannels in the MPC group do become active.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All using FICON CTC/MPC connections.         *
    ****************************************************************
    * PROBLEM DESCRIPTION: FICON CTCs (AHHC/MPC/CTC) subchannel    *
    *                      INOPs after partner is stopped and      *
    *                      restarted.  For MPC/AHHC connections,   *
    *                      the MPC group may become active even    *
    *                      though an individual READ or WRITE      *
    *                      device fails activation.                *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Sample Configuration:
    
     HOST1===FICON MPC===HOST2
    
    The problem is summarized as follows:
    
    1) A FICON MPC connection is active between two hosts.
    2) The MPC connection is stopped from HOST2.
    3) HOST1 recognizes the outage and tries to recover the
       MPC subchannels.
    4) HOST1 times out while initiating X-side channel programs.
    5) The MPC subchannels hang in Contact/Wait state at this
       point.
    6) At this point, HOST2 restarts the MPC connection.
    7) Upon restart, two asynchronous DE interrupts are received
       on HOST1.
    8) HOST1 should wait for the second asynchronous DE or an ATTN
       for each subchannel, prior to initiating a Y-side channel
       program.
    9) During the recovery of the MPC devices on HOST1, VTAM failed
       to reset the XCNURTRY bit when setting the state to
       Contact/Wait state.  This led VTAM to erroneously initiate
       the Y-side channel program upon the receipt of the first
       asynchronous DE.
    10) This caused the two sides to get out of synchronization with
       each other.  A queued ATTN (in IOS) from XID0 processing
       was presented to HOST1 after the XID0 exchange occurred.
       This caused HOST1 to read in the XID7, thinking the partner
       initiated the XID7 processing.
    11) Since HOST2 did not send XID7, HOST1 read in what it thought
       to be the XID7.  An INOP occurred on HOST1 while verifying
       the XID7 contents (ISTTSCXI).
    

Problem conclusion

  • ISTTSCXI - Has been modified to set the XCNURTRY bit on
               when setting the XCNSSFSM to Contact/Wait state.
               This will cause ISTTSCCA to wait for a second
               asynchronous DE prior to redriving the Y-side
               channel program.
    ISTTSC8E - Included for maintenance purposes.
    

Temporary fix

Comments

APAR Information

  • APAR number

    OA41355

  • Reported component name

    VTAM V4 MVS/ESA

  • Reported component ID

    569511701

  • Reported release

    1A0

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-01-31

  • Closed date

    2013-02-19

  • Last modified date

    2013-02-19

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

    OA37331

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

    UA68093

Modules/Macros

  • ISTTSCXI ISTTSC8E
    

Fix information

  • Fixed component name

    VTAM V4 MVS/ESA

  • Fixed component ID

    569511701

Applicable component levels

  • R1A0 PSY

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Document information


More support for:

z/OS family

Software version:

1A0

Operating system(s):

z/OS

Reference #:

OA41355

Modified date:

2013-02-19

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