OA40322: OSA EXPRESS QUITS PROCESSING INBOUND TRAFFIC

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• While processing a high volume of inbound data, the potential
  exists for the set of input buffers for an OSA Express (QDIO)
  device to become exhausted.  In some circumstances, the logic
  needed to refresh those buffers may not get invoked.  Once this
  occurs, inbound data arriving at the OSA that is destined for
  this one INTERFACE (or DEVICE/LINK pair) will no longer be
  processed.  Other INTERFACEs or stacks sharing this OSA port
  will be unaffected.
  
  External symptoms when this occurs can include:
  
   - If this is the only INTERFACE or DEVICE/LINK defined for a
     TCPIP stack, then all IP communication is lost.
  
   - If all devices defined for this stack are on the same LAN and
     this one owns the VIPAs, then communication to all VIPAs in
     that same subnet is lost.
  
   - If dynamic routing is enabled and this device is the primary
     interface for OSPF communication, EZZ7921I OSPF ADJACENCY
     FAILURE messages will occur.
  
  Occurrence of this problem can be confirmed by:
  
   - Repeated NETSTAT DEVLINKS (INTFNAME osadevice commands for
     the affected OSA show no change in the reported inbound
     statistics.
  
   - PINGs of the OSA's HOME address from other systems do not get
     a response, but PINGs of the HOME addresses for interfaces
     sharing the OSA are successful.
  
   - An OSAENTA trace shows packets arriving, but a PKTTRACE
     collected for this interface does not show those packets.
  
   - If a dump is collected, the SLSBs for the read queue (or one
     of the read queues if WORKLOADQ is configured) will have all
     of the statuses as either Inbound Ready (x'82') or Inbound
     Unavailable (x'80').
  

Local fix

• An immediate action would be to stop and restart the affected
  device:
  
     VARY  TCPIP,,STOP,osadevice
     VARY  TCPIP,,START,osadevice
  
  If this occurs often, consider increasing the number of input
  buffers allocated for an OSA.  The default is to use the QDIOSTG
  start option in VTAM, which itself defaults to MAX (64).  This
  can be increased up to 126, which can be performed dynamically
  (but each OSA will need to be recycled to pick up the new
  value).  Be aware though that this places a correspondingly
  increased demand for CSM storage, both Fixed and ECSA, which in
  turn requires more real storage frames on the system.  And this
  increase is (potentially) quadrupled if INBPERF DYNAMIC
  WORKLOADQ is configured.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using iQDIO or QDIO.                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Inbound traffic on an OSA Express       *
  *                      (QDIO) device is not processed after    *
  *                      its input buffers become exhausted.     *
  *                                                              *
  *                      In a dump, a bit in the DINCB           *
  *                      representing the device (DINCB_NoSPACs) *
  *                      is frozen on.                           *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Disabled Interrupt routine for QDIO (ISTLLCIE) is invoked by
  the system to process inbound data for an OSA device.  ?GETSPAC
  call from mainline fails because the input buffer set for the
  device is depleted. DINCB_NoSPACs is set on, and the DINCB PC
  PAB is supposed to be scheduled to replenish the buffers.
  This does not happen however, so inbound data can longer be
  processed unless the PAB is scheduled for some othe reason.
  DINCB_NoSPACs never gets turned off in this scenario either.
  

Problem conclusion

• ISTLLCIE will now turn on the local Sched_PCPAB bit when
  setting DINCB_NOSPACs.  This will ensure ISTLLCIE schedules
  the PAB prior to exit.
  
  ISTLLCM8 has been included for maintenance purposes only.
  

Temporary fix

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

Comments

APAR Information

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

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

  UA66997 UA66998 OA42455

Modules/Macros

• ISTLLCIE ISTLLCM8
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R1C0 PSY UA66997

     UP12/12/06 P F212 Ž

• R1D0 PSY UA66998

     UP12/12/06 P F212 Ž

Fix is available

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