A fix is available
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