OA43453: NEW FUNCTION - HYPERPAV XRC WORKLOAD-BASED WRITE PACING

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New Function APAR
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users at HBB7780 and above using             *
  *                 z/OS Global Mirror (XRC) workload-based      *
  *                 write pacing with HyperPAV                   *
  *                 enhanced write pacing functionality          *
  *                 delivered with APAR OA44004.                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: New function support for HyperPAV alias *
  *                      management.  HyperPAV aliases can be    *
  *                      unnecessarily consumed when write       *
  *                      pacing is employed in XRC environments. *
  *                      Support is added to detect when pacing  *
  *                      at certain levels is being done,        *
  *                      allowing z/OS to avoid consuming all    *
  *                      aliases for write I/Os that will be     *
  *                      paced.  D/T2107                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  New function in support of z/OS Global Mirror (XRC) workload-
  based write pacing.  In z/OS Global Mirror environments where
  HyperPAV technology is used on disk storage subsystems, a new
  workload importance-based scheme for injecting write pacing
  delays is used.  HyperPAV alias management is enhanced to
  recognize when significant delays are injected, and based on I/O
  importance will pace alias usage such that fewer aliases will be
  consumed by lesser importance I/Os that would otherwise be
  paced.
  
  Note that any time write pacing is induced, IOSQ time may
  be seen during pacing periods.  This support intends to allow
  higher importance I/Os to continue to use aliases in a
  graduated way based on importance, ensuring that higher
  importance work has a greater chance to exploit the parallelism
  that HyperPAV technology provides.
  
  Also required for complete support is OA41906 on production
  systems, and OA44004 is required on the System Data Mover system
  (see these APAR descriptions for details).
  

Problem conclusion

Temporary fix

Comments

• New function for HyperPAV alias management.
  HyperPAV alias management is enhanced to recognize when
  significant delays are injected, and based on I/O importance
  will pace alias usage such that fewer aliases will be consumed
  by lesser importance I/Os that would otherwise be paced.
  
  
  The following documentation change is being made:
     In MVS System Messages, Volume 7 (SA22-7637, SA38-0674)
  
     The following message is changed:
     IEE174I (form 6 of 35) hh.mm.ss DISPLAY M  idr  text
     Explanation: Where text is:
     DEVICE dev STATUS=status
     CHP nn  nn...
     PATH ONLINE Y|N  Y|N...
     CHP PHYSICALLY ONLINE Y|N  Y|N...
     PATH OPERATIONAL Y|N  Y|N...
     PATH ATTRIBUTES pa  pa...
      PATHS NOT VALIDATED
      PAV BASE AND ALIASES pp
      HYPERPAV ALIASES CONFIGURED = NNN
      HYPERPAV DEVICE OPERATING IN BASEONLY MODE
   |  ALIAS USAGE THROTTLED FOR IMPORTANCE LEVELS n-6
   |  ALIAS USAGE THROTTLED FOR IMPORTANCE LEVEL 6
      FUNCTIONS ENABLED = functions
      ALTERNATE SUBCHANNEL SET DEVICE sdddd IS ACTIVE
      DEVICE STOPPED BY HYPERSWAP
     *************** SYMBOL EXPLANATIONS ***************
     PF=PREFERRED NP=NON-PREFERRED NS=NOT SPECIFIED
     ...
     HYPERPAV DEVICE OPERATING IN BASE ONLYMODE
  
     This message indicates that the input device is a HyperPAV
     device that is temporarily not allowed to use alias devices
     due to some condition.
  
   |
   | ALIAS USAGE THROTTLED FOR IMPORTANCE LEVELS n-6
   |
   |  - Alias throttling is in effect for importance levels n
   |    through 6
   |
   | ALIAS USAGE THROTTLED FOR IMPORTANCE LEVEL 6
   |
   |  - Alias throttling is in effect for importance level 6.
     ...
  
     In MVS Data Areas, Volume 3 (IEFALCXT-IRARENF1)
     (GA32-0937,GA32-0855)
  
      In the IOQ chapter:
      ...
      OFFSET
        HEX  TYPE      LEN NAME         DESCRIPTION
      ====== ========= === ============ ==========================
   |     (0) STRUCTURE  80 IOQE
   |     (0) CHARACTER  80  IOQEXT      IOQ extension
         (0) CHARACTER   4   IOQEID     Control block ID ('IOQE ')
      ...
        (1D) BIT(8)      1    IOQEFLAG  IOQ Extension Flags
      ...
   |         .... ..1.         IOQEWPUC When on indicates to
   |                                    provide a unit check when
   |                                    this I/O is delayed
   |         .... ...1         IOQETID  Throttle-induced delay has
                                        been imposed for this I/O
      ...
        (38) BIT(16)     2     IOQEIOMS I/O management support dat
             1... ....         *        Reserved by hardware
             .111 ....         IOQE_IMPORTANCE  Importance level
      ...
   |    (40) CHARACTER   8   IOQEQUEUETIME The time the IOQ was
   |                                    queued.
   |    (48) CHARACTER   8   *          Reserved
      ...
  
      In the IOSDPAVA chapter, a new field is added in the
      extended format section of the PAVAENTRY mapping:
      ...
      OFFSET
        HEX  TYPE      LEN NAME          DESCRIPTION
      ====== ========= === ============= =========================
      ...
        (3C) CHARACTER  12 PAVAEFSTART   Start of area for
                                         extended format entry
                                         (version 3 and above)
        (3C) UNSIGNED    4  PAVAINTERRUPTDELAY
                                         Interrupt delay time
        (40) UNSIGNED    4  PAVAIOPRIORITYDELAY
                                         I/O priority delay
                                         time
   |    (44) UNSIGNED    4  PAVATHROTTLEDELAYCOUNT
   |                                     Accumulated count
   |                                     of I/Os that had imposed
   |                                     delay times
   |    (48) CHARACTER  24  *            Reserved
   KEYWORDS: HYPERPAV/K
  

APAR Information

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

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

  UA90743 UA90744 UA90745 UA75783

Modules/Macros

• IEAIPL71 IECDIOQ  IECVIOPM IECVIOSI IEEDMDEV
  IEEVDMCU IOSCACDR IOSCDCDR IOSCDCM  IOSCFCH2 IOSDDSE  IOSDPAVA
  IOSFQVIR IOSHSSUB IOSIUCB  IOSPURGC IOSRCHDS IOSRMIHI IOSRMIHP
  IOSRSCH  IOSVBALC IOSVCMBO IOSVCMES IOSVCMUB IOSVCMUD IOSVCUIN
  IOSVDATA IOSVFBND IOSVFMTH IOSVFMTU IOSVIMBC IOSVIOQM IOSVIRBA
  IOSVIRBD IOSVLSSR IOSVMOD1 IOSVNPTH IOSVSCBX IOSVSCHR IOSVSDEX
  IOSVSLFD IOSVSLFI IOSVSPSP IOSVSSCH IOSVSSCQ IOSVSWAP IOSVSWDG
  IOSVSWMN IOSVTRAN IOSVUCOP IOSVUSER
  

Fix information

• Fixed component name

  IOS

• Fixed component ID

  5752SC1C3

Applicable component levels

• R78H PSY UA75783

     UP15/01/10 P F501

• R780 PSY UA90743

     UP15/01/10 P F501

• R790 PSY UA90744

     UP15/01/10 P F501

Fix is available

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