OA54688: NEW FUNCTION - ASYNCHRONOUS CROSS-INVALIDATION FOR COUPLING FACILITY CACHE STRUCTURES

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New function
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  *  Installations exploiting parallel sysplex at                *
  *                 HBB77A0 (z/OS V2R2) and above, and using     *
  *                 coupling facility (CF) cache structures for  *
  *                 transactional data processing.               *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  *  New function: Improve performance for                       *
  *                      transactions involving multiple CF      *
  *                      cache requests by processing            *
  *                      cross-invalidation asynchronously.      *
  *                                                              *
  *                      Diagnostic data required when CF        *
  *                      information missing in CFRM.            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  *  Install the applicable PTF on each system in                *
  *                 the sysplex.  A rolling IPL is sufficient to *
  *                 activate the fix.                            *
  ****************************************************************
  Cross-invalidation processing ensures cache coherency by
  notifying structure connectors when local copies of a cached
  data item are no longer current.  Cross-invalidation requires
  communication between the CF and other LPARs, which are likely
  to be on separate processors.  Today, cross-invalidation (XI)
  notifications must occur synchronously as part of the command
  (IXLCACHE request) that initiated the changes to the cached
  item, and the command cannot complete until all affected
  connectors have been notified.  That synchronous communication
  imposes a delay that degrades command performance.  For
  transactions comprising multiple cache requests, the cumulative
  delay in command completion can be significant, especially when
  some connectors reside on CPCs distant from the one housing the
  CF.  New function is required to reduce that delay.
  
  Diagnostic data is required when information describing
  connected CFs is missing in CFRM.
  
  E3906/K E3907/K
  SYSPLEXDS
  

Problem conclusion

Temporary fix

Comments

• OA54688 introduces support for asynchronous cross-invalidation.
  In this protocol, the CF's communication to notify connectors of
  data invalidation can be initiated asynchronously with respect
  to the IXLCACHE request.  In a transaction involving multiple
  cache requests, the parallelism obtained by allowing XI
  notifications to execute asynchronously may reduce both request
  service time and transaction elapsed time, thus improving
  overall application throughput.  Asynchronous processing of
  cross-invalidation has several important implications:
  
  o To ensure data integrity, the exploiting application must
    "synch up" before committing a transaction to ensure that all
    outstanding XI notifications have been delivered.  A new API,
    IXLAXISN, provides the mechanism for accomplishing that
    synchronization.
  
    o The CF assigns a unique, monotonically-increasing sequence
      number to every set of XI notifications initiated by a
      connector request.  The sequence numbers are assigned on a
      per-connector basis.
  
    o Every IXLCACHE request that initiates asynchronous XI
      notifications will return a sequence number to the requestor
      in the cache answer area mapped by IXLYCAA.  The application
      is responsible for tracking those sequence numbers and
      correlating them with in-flight transactions.
  
    o Before transaction commit, the connector must invoke the new
      IXLAXISN API to determine the completion status of the XI
      notifications associated with the transaction.  It is only
      necessary to wait for completion of the highest-valued
      sequence number returned during the transaction.  When XIs
      represented by that sequence number are complete, all XIs
      represented by lower-valued sequence numbers are also
      complete.
  
  o Because the asynchronous XI protocol requires active connector
    participation, connectors must signify their ability to
    exploit this protocol at connect time.  The new IXLCONN
    ASYNCXI keyword provides the mechanism by which connectors
    indicate their intent to exploit asynchronous XI.  Setting
    ASYNCXI=1 indicates that by default, the CF will use the
    asynchronous XI protocol for all IXLCACHE requests initiated
    by the connector.  ASYNCXI=1 is meaningful only when the
    structure is allocated in a CFLEVEL 23 CF and the system on
    which the connector resides supports the asynchronous XI
    protocol.
  
  o Asynchronous XI notification improves performance only for
    IXLCACHE requests initiated within the scope of a transaction,
    when the completion of XI notifications for multiple IXLCACHE
    requests can be determined by a single IXLAXISN invocation.
    For IXLCACHE requests that are not expected to benefit from
    asynchronous XI notifications, the exploiting application
    should use the new IXLCACHE AXIOVERRIDE keyword to specify
    that the CF is to use the original synchronous XI delivery
    protocol.  Setting IXLCACHE AXIOVERRIDE=1 overrides the
    default specification established by IXLCONN ASYNCXI=1 for the
    current IXLCACHE request only.
  
  o If a connector exploiting asynchronous XI fails during a
    transaction, the application must ensure that any outstanding
    XI notifications have completed before allowing any peer
    connector to access resources left in doubt.
  
    o Transaction serialization held by the failed connector must
      not be released (or equivalent serialization must be
      obtained) until XIs have completed.
  
    o When the failed connector reconnects, asynchronous XIs
      initiated by the original connector instance are known to
      be complete.
  
  
  Diagnostic data is collected when information describing
  connected CFs is missing in CFRM.
  
  
  Publication updates associated with this APAR can be found at
  http://publibz.boulder.ibm.com/zoslib/pdf/OA54688.pdf
  
  Summary of updates:
  
  z/OS MVS Programming: Sysplex Services Guide (SA23-1400)
  --------------------------------------------------------
  o Sysplex Services for Communication (XCF)
    o Using the Cross-System Coupling Facility (XCF)
      o Obtaining XCF Information
        o Using the IXCQUERY Macro
          o Information returned inline to IXCQUERY (changed)
  o Sysplex Services for Data Sharing (XES)
    o Connection Services
      o Connecting to a Coupling Facility Structure
        o Connecting to a Cache Structure (changed)
          o Specifying Asynchronous or Synchronous Cross-
            Invalidate Processing (new)
        o Disconnecting from a Coupling Facility Structure
          o Persistent considerations
            o Handling Resources for a Disconnection (changed)
        o Structure Rebuild Processing
          o Connecting to the New Structure
            o Using the IXLCONN Macro for Rebuilds (changed)
    o Using Cache Services
      o Cache Structure Allocation and Connection (changed)
      o Maintaining Data Consistency
        o Registering Interest in a Data Item and Validating Local
          Copies
          o Registering Interest in a Data Item (changed)
        o Deregistering Interest in a Data Item and Invalidating
          Local Copies
          o Invalidating Local Cache Copies of a Data Item
            (changed)
          o Overriding the Asynchronous Cross-Invalidate
            Processing (new)
      o Serializing and Managing Access to Shared Data
        o Serialization considerations when requesting
          asynchronous cross-invalidations (new)
      o Receiving Information from a Request
        o Defining an Answer Area (ANSAREA) (changed)
          o Specifying the IXLYCAA Level (changed)
    o Supplementary List, Lock, and Cache Services
      o Using the IXLAXISN Macro (new)
  
  
  z/OS MVS Programming: Sysplex Services Reference (SA38-0658)
  ------------------------------------------------------------
  o IXLADUPX (changed)
  o IXLAXISN (new)
  o IXLCONN (changed)
  o IXLCACHE
    o Understanding IXLCACHE version support (changed)
    o IXLCACHE REQUEST=CROSS_INVAL (changed)
    o IXLCACHE REQUEST=CROSS_INVALLIST (changed)
    o IXLCACHE REQUEST=DELETE_NAME (changed)
    o IXLCACHE REQUEST=DELETE_NAMELIST (changed)
    o IXLCACHE REQUEST=READ_DATA (changed)
    o IXLCACHE REQUEST=REG_NAMELIST (changed)
    o IXLCACHE REQUEST=WRITE_DATA (changed)
    o IXLCACHE REQUEST=WRITE_DATALIST (changed)
  
  
  z/OS V2R2 MVS Data Areas Vol. 3 (GA32-0937)
  -------------------------------------------
  o IXCYQUAA (changed)
  o IXLYCAA (changed)
  o IXLYCON (changed)
  o IXLYDDIB (changed)
  ×**** PE19/10/18 FIX IN ERROR. SEE APAR OA58507  FOR DESCRIPTION
  ×**** PE19/11/08 FIX IN ERROR. SEE APAR OA58507  FOR DESCRIPTION
  

APAR Information

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

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

  UA97982 UA97985

Modules/Macros

• IXLM2DIE IXLR1RES IXLR1GLB IXLYDDIB IXLF1CON IXLR1GLC IXLR1ALT
  IXLYCAA  IXLR1ALR IXLR1ADS IXCYQUAA IXLF1VTU IXLF1RTR IXLC1DCN
  IXLF1VTL IXLF1VCX IXCL2ATC IXLM2DRL IXLR1DIA IXLF1VCN IXLX1EER
  IXLC1CON IXCL2ATH IXLC1EOT IXCL2ASR IXLR1AXI IXLM1MS2 IXLCONN
  IXLX1AEI IXLAXISN IXLR1RT  IXLF1TX2 IXLF1LKM IXLF1SUL IXLM2DSP
  IXLR1CRR IXLR2SSD IXLF1VSC IXLM2MR  IXLF1TFT IXLM1TMR IXLR1GRT
  IXLI1LPX IXLYCON  IXLM1REC IXLR1UNL IXLC2LBF IXCI2PH1 IXLR1BUN
  IXLCACHE IXLF1STK IXLF1TRC IXLM1TBL IXLF1RES IXLF1TF4 IXLE1REC
  IXLR1SYN IXLR1CAC IXLF1NAM IXCL2AAT IXLR1SUS IXLR1LKR IXLM2DR
  IXLI1SIN IXLR1RSM IXLR1LCK
  

Fix information

• Fixed component name

  CROSS SYS.EXT.S

• Fixed component ID

  5752SCIXL

Applicable component levels

• R7A0 PSY UA97985

     UP18/11/30 P F811  

• R7B0 PSY UA97982

     UP18/11/30 P F811  

Fix is available

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