OA49227: NEW FUNCTION - IMPROVE FRRECOV FROMDUMP MULTI-TASKING PERFORMANCE BY AVOIDING EXCLUSIVE ENQ ON GENERIC RESOURCE

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New Function APAR
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DFSMShsm V1R13 and later users of the    *
  *                 FRRECOV COPYPOOL FROMDUMP command.           *
  ****************************************************************
  * PROBLEM DESCRIPTION: During Full Volume Restore, when DSS    *
  *                      performs the allocation for it's        *
  *                      temporary data set or temporary work    *
  *                      area for ICKDSF to use when building    *
  *                      the VTOC index, it does not know which  *
  *                      volser will be used for the allocate,   *
  *                      so an exclusive NONSPEC ENQ is          *
  *                      obtained.                               *
  *                                                              *
  *                      Up to 64 recovery tasks from FlashCopy  *
  *                      DUMP can be done in parallel in each    *
  *                      environment using SETSYS parm           *
  *                      "MAXCOPYPOOLTASKS (FRRECOV(nn))", but   *
  *                      in reality, due to an exclusive ENQ on  *
  *                      the generic NONSPEC resource each task  *
  *                      essentially processes serially instead  *
  *                      of in parallel.                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A customer requirement for both DSS and HSM for 'performance
  deficiency'. In theory, up to 64 recovery tasks from FlashCopy
  DUMP can be done in parallel in each environment using SETSYS
  parm "MAXCOPYPOOLTASKS (FRRECOV(nn))". In reality, due to an
  exclusive ENQ on the generic NONSPEC resource used to prevent
  lockouts involviing SYSZTIOT and SYSVTOC, each task essentially
  processes serially instead of in parallel.
  
  This behavior is not acceptable to the customer expecting to
  reduce recovery times with the parallel processing.
  

Problem conclusion

Temporary fix

Comments

• A method is needed for users to specify whether increased
  throughput is more important to them than the possibility of
  the enqueue lockout.
  
  Users who wish to bypass this enqueue process and are willing to
  accept the possibility of the enqueue lockout described by this
  APAR can do so using the following DFSMShsm PATCH command:
  
     PATCH .MCVT.+3D5 BITS(.......1)
  
  Applying the PTF for this APAR makes this function available.
  The function is enabled only when PATCHed on by the user and
  applies only to FRRECOV CP FROMDUMP processing.
  
  DFSMS Installation and Customization Guide, publication number
  SC23686902, Add the following information to Chapter 16.
  Tuning DFSMShsm. Under the section headed 'Changing parameters
  passed to DFSMSdss' and immediately prior to 'Enabling ABARS
  ABACKUP and....', Add the following:
  
  To improve FRRECOV COPYPOOL FROMDUMP performance, you may want
  to bypass the EXCLUSIVE NONSPEC ENQ that is performed when DSS
  allocates it's temorary data set or temporary work area for
  ICKDSF to use when building the VTOC index. The enqueue is
  designed to prevent a lockout that may occur involving SYSZTIOT
  and SYSVTOC if the temporary data set allocation is directed to
  a volume that DFSMShsm is dumping or restoring and an EOV is
  issued.
  
  Users who wish to bypass this enqueue process and are willing
  to accept the possibility of the enqueue lockout between SYZTIOT
  and SYSVTOC can do so using the following DFSMShsm PATCH
  command:
  
  To activate the feature, issue the following:
    PATCH .MCVT.+3D5 BITS(.......1)
  
  To deactivate the feature, issue the following:
    PATCH .MCVT.+3D5 BITS(.......0)
  
  The z/OS DFSMShsm Data Areas book, publication number
  GC14750402 needs new bit space documented. In Table 107. MCVT -
  Management Communication Vector table, Add the following
  information:
  
     Offsets
  Decimal (Hex)  BITSTRING  Length Name           Description
   981    (3D5)  .... ...1  MCVTF_NOEXCL_NSPLOCK  When set to 1,
                                                  set ADREID0
                                                  flag to notify
                                                  DFSMSdss to
                                                  bypass EXCL
                                                  NONSPEC ENQ
                                                  for VTOC index
                                                  build process.
  
  Table 108. MCVT Data Area Cross-Reference Table needs the
  following field and related information added:
  
  MCVTF_NOEXCL_NSPLOCK  3D5   01    3
  

APAR Information

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

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

  OA49228 UA81182 UA81183 UA81184

Modules/Macros

• ARCREUIM
  

Fix information

• Fixed component name

  DFSMSHSM, ISMF

• Fixed component ID

  5695DF170

Applicable component levels

• RD10 PSY UA81182

     UP16/04/15 P F604

• R210 PSY UA81183

     UP16/04/15 P F604

• R220 PSY UA81184

     UP16/04/15 P F604

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.