PM15036: BH COMMAND RESULTS IN MSGIRX0040I - ERROR RUNNING ADB2ZBH WHEN DB2 RANDOM GETPAGE COUNTER WRAPS. FFA10 PM27184

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• In DB2 Administration Tool for z/OS use of BH command to display
  Buffer Pool Hit Ratio can result in REXX error if DB2 counter
  values have wrapped. Error messages appear similar to:
  .
  202 +++      randhr = format(((randgp - randio)/randgp)*100,3,2)
   54 +++     call addline
  IRX0040I Error running ADB2ZBH , line 202: Incorrect call to
           routine
  Function : SELECT CMD(%ADB2ZBH ADB2ZBH1 ADB2ZBH2 )
  Retcode  : 20040
  Zerrmsg  : ISPT034
  Zerrsm   : Table is not open
  Zerrlm   : Database 2 Administration Tool.
  .
  One indication of wrapped DB2 counters appears in display of
  BUFFERPOOL where we see value of random GETPAGE is higher than
  Sync Read I/O, which appears similar to the following message:
  .
  DSNB411I  *DP02 RANDOM GETPAGE    =445103781 SYNC READ I/O (R)
                                   =1021688031
  .
  DB2 Random Getpage counter wraps at 4GB . Once wrap occurs,
  buffer pool hit ratio calculation can yield incorrect results
  as well as REXX error message.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of DB2 Administration Tool for         *
  *                 z/OS who use the System Administration       *
  *                 command 'BH' to display the buffer           *
  *                 pool hit ratio.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: When using the DB2 Administration       *
  *                      Tool for z/OS BH command to             *
  *                      display the Buffer Pool Hit Ratio,      *
  *                      a REXX error can occur if the DB2       *
  *                      counter values have wrapped.            *
  *                      Error messages appear similar to:       *
  *                      .                                       *
  *                      202 +++      randhr = format(((randgp   *
  *                      - randio)/randgp)*100,3,2)              *
  *                      54 +++     call addline                 *
  *                      IRX0040I Error running ADB2ZBH ,        *
  *                      line 202: Incorrect call to routine     *
  *                      Function : SELECT CMD(%ADB2ZBH          *
  *                      ADB2ZBH1 ADB2ZBH2 )                     *
  *                      Retcode  : 20040                        *
  *                      Zerrmsg  : ISPT034                      *
  *                      Zerrsm   : Table is not open            *
  *                      Zerrlm   : Database 2 Administration    *
  *                                 Tool.                        *
  *                                                              *
  *                      One indication of wrapped DB2           *
  *                      counters appears in the display         *
  *                      of BUFFERPOOL where we see              *
  *                      the value of the Random GETPAGE         *
  *                      is higher than the Sync Read I/O,       *
  *                      which appears similar to the            *
  *                      following message:                      *
  *                      .                                       *
  *                      DSNB411I  *DP02 RANDOM                  *
  *                      GETPAGE   =445103781 SYNC               *
  *                      READ I/O (R)  =1021688031               *
  *                                                              *
  *                      DB2 Random GETPAGE counter              *
  *                      wraps at 4GB. Once the wrap             *
  *                      occurs, the buffer pool hit ratio       *
  *                      calculation can yield incorrect         *
  *                      results, as well as a REXX              *
  *                      error message.                          *
  ****************************************************************
  * RECOMMENDATION: Apply The PTF.                               *
  ****************************************************************
  The BH command's REXX EXEC ADB2ZBH was not
  checking if the SYNC Read I/O value was greater than
  the RANDOM GETPAGE.
  

Problem conclusion

• The REXX EXEC has been changed to check the
  SYNC I/O vs RANDOM GETPAGE, and if SYNC I/O is
  greater a message will be displayed on panel ADB2ZBH2
  "Display Buffer Pool Hit Rates":
  
  Short Message='Hit Ratio not calculated'
  
  Using PF1 the long message will be seen:
  
  Long Message='SYNC Read I/O larger than Random
  Getpages, may be due to counters wrapping or poor
  prefetch performance'
  

Temporary fix

Comments

APAR Information

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

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

  UK61708

Modules/Macros

•    ADB2ZBH
  

Fix information

• Fixed component name

  DB2 ADMIN TOOL

• Fixed component ID

  568851500

Applicable component levels

• R720 PSY UK61708

     UP10/11/02 P F011

Fix is available

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