PI52430: A TIMING CONDITION IN LOG WRITE THAT COULD LEAD TO ABEND 0C4 DSNJW127+1E58.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When DSNJW127 process log request check, it picked up a bad RBA
  value as the RBA to write, thus caused the 0C4 DSNJW127+1E58.
  DSNJW127 WOULD HAVE ABENDED ELSEWHERE OR WE HAVE AN INFINITE
  LOOP WHILE DSNJW127 CATCH UP A BAD RBA VALUE.
  Additional Symptom:
  ABENDS04E reason code 00D10269 issued from module DSNJW127
  due to register 4 being zero in sub-routine YBFRWRT.
  ABEND04E ABEND 04E ABND=04E-00D10269 rsn x'00D10269'
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Version 11 users of DB2 for zOS that     *
  *                 have converted the BSDS data sets with the   *
  *                 DSNJCNVT utility to use 10 byte RBA values.  *
  ****************************************************************
  * PROBLEM DESCRIPTION: ABEND0C4 RC10 at DSNJW127 received and  *
  *                      DB2 terminates with RC00D10251.         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When the log buffers are obtained during DB2 restart, they are
  initialized to zeros. There is a small timing window in the
  10-byte RBA log record build routine that can cause log readers
  to incorrectly detect a log read buffer is in 6-byte RBA format
  even though the BSDS data sets have been converted to use
  10-byte RBA value.
  
  In the reported scenario, a request came in to have all log
  buffers up to current log buffer write out to disk. The request
  hit the timing window when checking the log buffer format, and
  used an invalid 6-byte RBA as the RBA value to write up to.
  The invalid RBA value is higher than highest RBA written on
  the system, which caused the physical log writer to look beyond
  current log buffer and resulted in ABEND0C4 RC10 in DSNJW127.
  
  The 10-byte log buffer format indicator is set in each log
  buffer after it has been used. The indicator needs to be set
  earlier in the log record build process to close this timing
  window.
  
  Please note that this timing window is closed after the log
  buffers have been used once. The 6-byte RBA log record build
  routine does not set this indicator, so this timing window does
  not exist before the BSDS has been converted to the 10-byte
  RBA format.
  
  Reported symptoms include: ABEN0C4 RC10 in DSNJW127 and
  MSGDSNJ013I with error code RC00D10264. Additional symptoms
  may be possible, such as ABEND04E RC00D10264 in DSNJW127.
  

Problem conclusion

• The new buffer initialization code in the 10-byte RBA log
  record build routine (DSNJW011) has been changed.
  
  Additional keywords: DB2EXTRBA/K
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UI33435

Modules/Macros

•    DSNJW011
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI33435

     UP15/12/16 P F512 Ž

Fix is available

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