VM66037: ABENDSXA004 DURING VSWITCH LACP MARKER PROCESSING

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Abendsxa004 sxa004 occurs processing a large number of UDP
  packets being sent to the physical network.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All customers using a z/VM VSwitch with a    *
  *                 Link Aggregation Port Group configuration.   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  A VSwitch configured with a Link Aggregated (LAG) UpLink Port
  may encounter a SXA004 ABEND when moving workload around within
  the LAG.  This may occur if one or more guests are transmitting
  a very large number of UDP Packets to the external network at
  the same time z/VM is performing LACP Marker Processing to move
  workload around.  Marker Processing requires the VSwitch to
  buffer out going packets to a specific OSA Port, until a Marker
  Response is returned from the connected physical partner switch.
  If the physical switch is slow to respond and one or more guests
  continually transmit a large number of packets for z/VM to
  buffer, it's possible we can exhaust all storage in the system
  execution space with NDMBK Blocks queued for transmission to the
  external network.
  

Problem conclusion

• VSwitch Marker Processing is enhanced to take the appropriate
  action to limit the number of NDMBKs queued on the Stage I and
  II Suspension Queues.  A new High Capacity Time-Out is added to
  the existing Marker Time-Out support.  Its purpose is to slow up
  a suspended high capacity guest when a low limit threshold is
  reached and terminate Marker Processing when a high limit
  threshold is hit.  The action taken depends on the current count
  of NDMBKs and the time they are on the suspension queue.
  

Temporary fix

• *********
  * HIPER *
  *********
  FOR RELEASE VM/ESA CP/ESA R540 :
  PREREQ: VM65672
  CO-REQ: NONE
  IF-REQ: NONE
  FOR RELEASE VM/ESA CP/ESA R630 :
  PREREQ: VM65583
  CO-REQ: NONE
  IF-REQ: NONE
  FOR RELEASE VM/ESA CP/ESA R640 :
  PREREQ: NONE
  CO-REQ: NONE
  IF-REQ: NONE
  

Comments

APAR Information

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

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

  UM35176 UM35177 UM35178

Modules/Macros

• HCPSWA
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R540 PSY UM35176

     UP17/07/25 I 1000 ¢

• R630 PSY UM35177

     UP17/07/25 I 1000 ¢

• R640 PSY UM35178

     UP17/07/25 P 1702 ¢

Fix is available

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