OA60274: A SYSZVVDS DEADLOCK MAY OCCUR IF PERFORMING DFSMSHSM RECALLS FROM MULTIPLE SYSTEMS DIRECTED TO THE SAME TARGET VOLSER

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When multiple HSM RECALLs occur simultaneously from multiple
  systems, and they are directed to the same output volume, a
  small timing window exists that may allow a SYSVVDS deadlock to
  occur.
  For example:
  RECALL #1 on System A will read the target VVR for update and
  obtain serialization. In the small window before RECALL #1
  attempts to update the target VVR, RECALL #2 makes the same read
  request from System B.  When RECALL #1 attempts to update the
  VVR, it cannot obtain the proper serialization because of
  actions being performed by RECALL #2.  RECALL #2 cannot proceed
  because of the serialization held by RECALL #1, thus causing a
  deadlock.
  The timing window with the events occurring in such a manner is
  very small.
  
  KNOWN IMPACT:
  This may cause ENQUE HANG for SYSZVVDS, thus causing some
  processes not to complete.
  
  ADDITIONAL SYMPTOMS:
  HANG
  WAIT
  VVDs
  VVR
  ENQUEUE
  
  msgarc1170I rsn07 during recall of GDG generations and
  MSGADR497e rc50 rsn06 when attempting to update the VVR/NVR's
  class transition date.  This indicates the VVR/NVR does not
  exist even though DFSMSdss created it successfully.  Data set
  is recataloged on the volume as well msgarc0950I error invoking
  catalog delete rc50 rsn06 and msgarc0937I failed to scratch SMS
  managed data set.
  Application then attempts to open the data set which fails
  with msgiec143I 213-2C abend213 rc2c.
  
  CATKEYS: CAT2020 CATHANG CATDSS CATHSM CATVVDS
  

Local fix

• Catalog's Contention Detection Feature can be used to identify
  SYSZVVDS deadlocks, and automatically redrive a hung catalog
  task. This can be implemented with the Catalog Modify command:
  
  F CATALOG,CONTENTION(resource,wait_time,action-flags)
  
  Where resource = SYSZVVDS; wait_time = time in minutes to wait
  before taking action; and action-flags = NR which indicates
  'notify & redrive'.
  
  This can also be permanently implemented in the IGGCATxx parmlib
  member with:
  
  resource(minutes,action)
  
  where resource = SYSZVVDS; minutes = time in minutes to wait
  before taking action; and action = NR
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of DFSMShsm RECALL and DFSMSdss RESTORE that       *
  * simultaneously RECALL or RESTORE multiple data sets that are *
  * directed to the same output volume.                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * An application was triggering multiple HSM data set RECALLs  *
  * across multiple instances of HSM. SMS directed the data sets *
  * to the same volume. During these RECALLs a deadlock occurred *
  * on the SYSZVVDS resource of the target volume.               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  

Problem conclusion

• DFSMSdss has been modified to correct a serialization issue that
  caused a small timing window allowing the ENQUEUE deadlock
  during DFSMShsm RECALL.
  

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:

  UJ05016 UJ05017

Modules/Macros

• ADRRDVVR ADRSB212 ADRSB114 ADRMFAMS ADRDALOC ADRCNVSM ADRPREVS
  ADRTDLOG
  

Fix information

• Fixed component name

  DFSMSDSS, ISMF

• Fixed component ID

  5695DF175

Applicable component levels

• R240 PSY UJ05017

     UP21/03/16 P F103

• R230 PSY UJ05016

     UP21/03/16 P F103

Fix is available

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