OA38613: System Logger enhancements in log stream offload management

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• IN SUPPORT OF NEW FUNCTION
  
  Keywords:
      E2827/K
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of HBB7780 and above supported         *
  *                 releases using System Logger Services        *
  *                 and log stream resources                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Singular system logger log stream       *
  *                      offload/data set management tasking can *
  *                      impede concurrent offload activity.     *
  *                                                              *
  *                      Unnecessary synchronous requests from   *
  *                      IXGBRWSE request=end operation to       *
  *                      logger offload/data set management task *
  *                      can cause delays in other log stream    *
  *                      browse processing.                      *
  *                                                              *
  *                      Logger needs to maintain more up to     *
  *                      date log stream "offload" information   *
  *                      in the LOGR CDS following an offload,   *
  *                      meaning after log data moved/deleted    *
  *                      from primary and potentially written to *
  *                      secondary, especially when a staging    *
  *                      data set is not used for duplexing the  *
  *                      log data.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  System logger uses a singular set of sub-tasks for log stream
  data set management during offload and data set deletion
  activities.  Any lengthy activity for one log stream can impact
  the requests of another log stream.  Logger has task monitoring
  in the event of any particular offload thread being inhibited
  for an extended period.  However, there is very little done when
  a large amount of requests are queued to the same sub-task and
  each request takes some time.  The cumulative effect is that the
  offload or log stream operation can be impeded by the long list
  for the same sub-task.
  
  
  During the operation for an IXGBRWSE REQUEST=END, logger issues
  a synchronous request to the logstream offload miscellaneous
  service task.  Any delays in getting this request processed, can
  result in delays in the browse request completing.  While this
  browse request is being processed, logger holds the log stream
  "browse level" latch exclusive.  Other log stream browse
  requests to the same log stream will be impeded until the
  synchronous request completes and the browse end processing
  releases this latch.  This synchronous request is extraneous and
  directed to an incorrect logger task, and should be removed from
  the browse end processing.
  
  
  Logger does not always reflect the latest log stream offload
  activity results in the LOGR CDS log stream record (LSR), so if
  a double failure of both the primary and duplex copies of log
  data occurs it can cause system logger to lose state information
  about the log stream.  This can lead to an unexpected loss of
  log data when the older LOGR CDS state data is used  during
  later log stream recovery processing.
  

Problem conclusion

Temporary fix

Comments

• System logger has been enhanced to provide improvements in the
  areas stated in the problem description section.
  
  See the Enhancement and Documentation sections for additional
  details.
  
  
  
  Activation of this fix on each system requires an IPL.
  
  This fix may be applied to one system at a time in the sysplex.
  
  Systems with and without the fix activated can coexist in the
  same sysplex.
  
  
   Additional Searchable keywords:
     SYSPLEXDS
  
  
  ENHANCEMENT INFO FOR OA38613
  * FUNCTION AFFECTED: BCP                             (OA38613) *
  *                      Logger                                  *
  *                        Logstream                             *
  *                          DASDONLY Logstream                  *
  *                          CF Logstream                        *
  *                          IXGBRWSE                            *
  *                        Offload Processing                    *
  * DESCRIPTION      : Enhancement                               *
  * TIMING           : As Needed                                 *
  
  System Logger has been enhanced to provide more task separation
  between Coupling Facility-based and DASD-only log streams.  This
  is intended to support higher rates of log stream offload data
  set allocations, reduce primary storage full conditions, and
  support higher overall concurrent log stream offload rates.  See
  the Documentation section for more details.
  
  
  The extraneous synchronous request during log stream browse end
  processing to the log stream miscellaneous service task has been
  removed.  This further reduces the interference between log
  stream offload and browse activity.
  
  
  Logger now records the latest log stream offload activity in the
  LOGR CDS log stream record (LSR) to allow for more complete log
  stream recovery.
  
  
  
  DOCUMENTATION INFO FOR OA38613
  * FUNCTION AFFECTED: BCP                             (OA38613) *
  *                      Logger                                  *
  *                        Logstream                             *
  *                        Offload Processing                    *
  *                        Miscellaneous                         *
  *                          Messages                            *
  * DESCRIPTION      : Documentation updates                     *
  * TIMING           : As Needed                                 *
  
  Summary of changed Publications-
    z/OS MVS Diagnosis: Reference                GA22758816
    z/OS MVS Setting Up a Sysplex                SA22762521
          (see PTF cover letter for changes to above publication)
    z/OS MVS System Messages: Vol 10 (IXC-IZP)   SA22764024
  
  
   Book Title -
        z/OS MVS  Diagnosis Reference Chapter 2
  
     +--- LOCATION IN PUBLICATION ---------------------------+
     |                                                       |
     | System Logger                                         |
     | + Correcting common problems                          |
     |   Resolving system logger allocation errors           |
     |  (see PTF cover letter for above changes)             |
     | + Restarting the system logger address space          |
     |                                                       |
     +-------------------------------------------------------+
  
   Restarting the system logger address space
  
    If it is necessary to restart the IXGLOGR address space to
    correct problems or apply maintenance, then the following
    procedure is recommended:
  
    1. Take action to cause any log stream connectors (exploiters)
       to disconnect from their log stream(s).  You can use the
       following commands to identify any connectors and which log
       streams need attention.
  
       Display LOGGER,C,JOB=*
       Display LOGGER,C,LSN=*
  
       When there are no log stream connections remaining on the
       system, IXG601I message output will indicate 'NO MATCHING
       INFORMATION FOUND.'
  
    2. Issue the command FORCE IXGLOGR,ARM and wait for it to
       complete (refer to message IXG067E in z/OS MVS System
       Messages, Vol 10 (IXC-IZP)).
  
    3. If this restart is to install maintenance, ensure it is
       applied at this point.
  
    4. Issue the command START IXGLOGRS to restart system logger.
  
    5. Take action to reconnect to log streams as needed.
  
    Note: The FORCE IXGLOGR,ARM command will cause disconnects for
    active log stream connections on the system and log stream
    requests will fail until logger is restarted. Applications
    with log stream connections may experience outages when system
    logger is unavailable. Log streams will need to be reconnected
    when system logger is available to resume operations.
  
    For more information on the START IXGLOGRS command, see
    "IXGLOGRS - Start the IXGLOGR server address space"  on page
    nn.  For more information on availability of the IXGLOGR
    address space, see "z/OS MVS Setting Up a Sysplex".
  
  
  
   Book Title -
        z/OS MVS System Messages:
  
     +--- LOCATION IN PUBLICATION ---------------------------+
     |                                                       |
     | updated messages:                                     |
     |   IXG271I IXG272E IXG310I IXG311I                     |
     |                                                       |
     | new messages:                                         |
     |   IXG285I IXG286I IXG287E IXG288E IXG289E             |
     |                                                       |
     +-------------------------------------------------------+
    (see PTF cover letter for message details)
  
  ×**** PE12/10/25 FIX IN ERROR. SEE APAR OA40633  FOR DESCRIPTION
  

APAR Information

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

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

  UA66195 UA66196

Modules/Macros

• HBB7780J IXGANSAA IXGA1AFP IXGA1ALC IXGA1AUS
  IXGA1DEL IXGA1DSM IXGA1HSM IXGA1MM  IXGA1MTX IXGA1RED IXGA1SWT
  IXGA1TSK IXGA1WRT IXGA2DEL IXGBLF01 IXGCONN  IXGC4CON IXGC4CTS
  IXGC4DIS IXGC4RBE IXGC4RCN IXGC4RPC IXGC4STE IXGDELET IXGD2DE1
  IXGD2WRT IXGE3CNF IXGE3SET IXGF1CAT IXGF1CMP IXGF1DSR IXGF1IWO
  IXGF1TRX IXGF1TTT IXGF1WOW IXGF2QRY IXGF2WRT IXGHC1CK IXGILSAB
  IXGIMPRT IXGINVF  IXGINVNT IXGINVP  IXGINVR  IXGIPFMT IXGIPRQE
  IXGIRUCA IXGISTRC IXGI3DSE IXGI3IN1 IXGI3IN2 IXGI3RPT IXGLOGEN
  IXGLOGJP IXGLRTSK IXGLSTSK IXGL1SUX IXGL1WRK IXGL2MON IXGL3SPC
  IXGL5SRB IXGMANSA IXGMLSAB IXGMPVTC IXGP1DSP IXGP3DSP IXGQBUF
  IXGQUERY IXGSFSTG IXGSXGP  IXGTTLBM IXGT1LBM IXGT2LBM IXGT3LBM
  IXGT4LBM IXGT5LBM IXGT6LBM IXGT7LBM IXGT8LBM IXGV1FMT IXGWORKT
  IXGWRITE IXGWZACC IXGWZASC IXGW1TSK IXGXMSG  IXGYCFMT IXGYLSAB
  IXGYSTBL
  

Fix information

• Fixed component name

  SYSTEM LOGGER

• Fixed component ID

  5752SCLOG

Applicable component levels

• R780 PSY UA66195

     UP12/08/22 P F208

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.