PJ40619: DASD CU FALL OVER TEST INPUT LIST SHUTDOW

APAR status

• Closed as program error.

Error description

• See Problem Summary.
  

Local fix

• na
  

Problem summary

• APAR NUMBER:  PJ40619
  PRODUCT:  z/TPF
  FUNCTIONAL AREA:  DASD
  SHIPPED IN PUT:  10
  
  ABSTRACT:
  Due to PJ32026, unplanned module down ECBs were stalled waiting
  for I/O after a control unit failure.
  
  PACKAGE CONTENTS:
  Source Segments:
  (C) base/rt/cyen.asm
  
  Object Only Binaries:
  None.
  
  Configuration Independent Binaries:
  (C) base/obj/cyen.o
  (C) base/load/CYEN.so
  
  Support Files:
  base/lst/cyen.lst
  base/lst/CYEN.map
  
  OTHER BINARIES TO BUILD: NO
  None.
  
  COMMENTS:
  In a base-only environment, unplanned module down calls CPAD
  with force, quiesce, and cleanup options to perform all module
  down tasks in one call. If the module being taken offline is
  the last module for that LSS, the cleanup option performs I/O
  to update the subsystem status table (SSST) header and cache
  fast write ID (CFWID) table. This cleanup I/O is done prior to
  purging the module queue for the module going offline. This
  means other ECBs relying on this module to complete I/O must
  wait for the cleanup I/O to finish before the module down ECB
  can purge the module queue and IOBs can be processed.
  
  If multiple module down conditions occur at the same time,
  there is a scenario where module down ECBs can become stalled
  waiting for I/O to complete. For example, an unplanned module
  down ECB is processing module A, is performing the cleanup
  tasks, and some of the I/O to update the CFWID table or SSST
  header is queued to module B. Module B goes offline and the
  unplanned module down ECB for module B also has to perform
  cleanup tasks. Because of record locking, the cleanup for
  module B can't proceed until the cleanup for module A finishes.
  However, one or more IOBs for module A's cleanup tasks are
  stalled on module B and will never finish. This will lead to an
  input list shutdown condition and an IPL would be required to
  clear the condition.
  

Problem conclusion

• SOLUTION:
  Segment cyen.asm is updated after label CYEN01B to perform
  module down processing in two steps. First, CPAD is called with
  the force and quiesce to force the module down and purge the
  module queue. After that is complete and the module is marked
  offline, CPAD is called a second time to perform the cleanup
  tasks including any I/O to update the SSST header and CFWID
  table. As a result of this change, module down ECBs should no
  longer be stalled waiting for I/O to complete.
  
  COREQS: NO
  None.
  
  MIGRATION CONSIDERATIONS: NO
  None.
  
  BUILD COMMANDS AND INSTRUCTIONS: YES
  #maketpf commands for linux
  maketpf -f CYEN cyen.o
  maketpf CYEN link TPF_VERIFY_LINK_REFS=NO
  maketpf CYEN link
  
  UPDATED INFORMATION UNITS: NO
  None.
  
  See your IBM representative if you need additional information.
  
  DOWNLOAD INSTRUCTIONS:
  http://www.ibm.com/software/htp/tpf/maint/maintztpf.html
  
  APAR URL:
  http://www.ibm.com/software/htp/tpf/ztpfmaint/put10/PJ40619.htm
  

Temporary fix

Comments

APAR Information

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

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

Fix information

• Fixed component name

  Z/TPF

• Fixed component ID

  5748T1501

Applicable component levels

• R110 PSY UP

     110