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OA30667: HIPERSOCKETS (IQDIO) CONNECTION TIMES OUT WHILE RUNNING UNDER Z/VM

A fix is available

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APAR status

  • Closed as unreproducible in next release.

Error description

  • Hipersockets (iQDIO) connection times out while running under
    z/VM. Configuration and route information would seem correct
    yet connections between z/VM systems would time out while
    connectivity between systems in each z/VM would seem to be
    working fine.
    
    When debugging this issue, VTAM internal trace (option CIA
    active) would show ODPK entries not detecting any incoming
    packet, only outgoing. In addition, traces would show that
    all SBALEs (= iQDIO read channels) are not active.
    
    The reason for this to happen is that the CHSC x'24' issued to
    determine wich SIGA is required is done too early (prior to
    establishing-QDIO-Queues)  for it to work correctly in a
    virtual machine. The result is z/OS not issuing SIGA-s
    appropriately.
    

Local fix

  • No local fix.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All running QDIO or iQDIO devices on a       *
    *                 second level z/OS guest machine on z/VM.     *
    ****************************************************************
    * PROBLEM DESCRIPTION: Ping command times out when sent        *
    *                      over a QDIO (OSA) or iQDIO              *
    *                      (HiperSockets) connection and z/OS      *
    *                      is running as a guest virtual machine   *
    *                      under VM.                               *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The problem is summarized as follows:
    1) z/OS is running as a guest virtual machine under z/VM.
    2) TCP/IP has an active xQDIO (QDIO or iQDIO) connection
       to a z/Linux virtual machine.
    3) When running under z/VM, VTAM must synchronize its
       Direct I/O SLS (Storage List Structure) with VM and vice
       versa. These updates are made via the SIGA-r (Read), SIGA-w
       (Write) and SIGA-s (Synch) commands.
    4) In this specific case, VTAM learns early on (during
       control channel allocation) of which signals VTAM
       are required to issue if z/OS is running under z/VM.
    5) A CHSC (Channel Subsystem command) is issued to
       determine the adaptor characteristics for xQDIO
       devices.
    6) From problem diagnosis, it appears VTAM is issuing
       the CHSC much too early in the process.  VTAM must wait
       until it has issued the Write Init (Establish Queues)
       CCW for the adaptor characteristics data to be valid.
    7) In this specific case, the MPNCB_QDIOAC byte
       was set to x'A4' from module ISTINMAV.  This tells
       VTAM it only needs to issue SIGA-w (WRITE) commands.
       For this configuration, SIGA-r and SIGA-s bits should also
       be on to synchronize our Direct I/O tables with z/VM
       with respect to READ processing.  Since VTAM did not
       have these bits set, inbound data was not being processed
       by VTAM over this xQDIO connection.
    

Problem conclusion

Temporary fix

  • *********
    * HIPER *
    *********
    

Comments

  • ISTLLCAD - Updated segment INITDIN to initialize the
               adaptor characteristics byte in the DINCB
               (DINCB_QDIOAC), until the actual characteristics
               are learned from the CHSC command.
    ISTLLCD1 - Update segment IDXSTART to call a new segment,
               SIGABits, to learn the adaptor characteristics
               of the xQDIO device via the CHSC command.  This
               CHSC command is done in addition to the one issued
               earlier during the initialization process.
               The DINCB_QDIOAC byte is now set from the output of
               the new CHSC command, rather than copied from the
               MPNCB_QDIOAC field (from earlier CHSC output).
    ISTLLCM8 - Included for maintenance purposes.
    
    Partial route of D149026.
    

APAR Information

  • APAR number

    OA30667

  • Reported component name

    VTAM V4 MVS/ESA

  • Reported component ID

    569511701

  • Reported release

    190

  • Status

    CLOSED UR1

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2009-10-05

  • Closed date

    2009-10-13

  • Last modified date

    2010-01-05

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

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

    UA50681 UA50680 UA50682

Modules/Macros

  • ISTLLCAD ISTLLCD1 ISTLLCM8
    

Fix information

  • Fixed component name

    VTAM V4 MVS/ESA

  • Fixed component ID

    569511701

Applicable component levels

  • R1A0 PSY UA50680

       UP09/12/12 P F912

  • R1B0 PSY UA50681

       UP09/12/12 P F912

  • R190 PSY UA50682

       UP09/12/12 P F912

Fix is available

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Document Information

Modified date:
05 January 2010