PK79228: NEW FUNCTION SET MEMBER INELIGIBLE FOR RANDOMIZED GROUP ATTACH.

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• Set DB2 member ineligible for randomized group attach
  processing.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 Version 9 for z/OS users who use the *
  *                 group attach feature in a data sharing       *
  *                 environment.                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: Group attachment requests in DB2        *
  *                      Version 9 for z/OS do not work the same *
  *                      way as they did in DB2 Version 8 for    *
  *                      z/OS.  Members are selected at          *
  *                      random.                                 *
  *                                                              *
  *                      In addition, when there are             *
  *                      three or more members of an attachment  *
  *                      group, the randomizing algorithm        *
  *                      doesn't distribute group                *
  *                      attachment requests evenly.             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  DB2 Version 9 for z/OS introduces a new feature:  randomization
  of group attachment requests.  This is a change from DB2 Version
  8 for z/OS, where group attachment requests are always attempted
  in the order of DB2 subsystem initialization.  Some customers
  rely on this order to isolate batch processing from transaction
  processing.  This PTF provides a method to restore the DB2 V8
  group attachment behavior after migrating to DB2 V9, as well as
  providing additional flexibility.
  
  A related problem is that when there are three or more members
  of a data sharing group, the DB2 V9 randomization algorithm
  tends to primarily favor the first and last members of a group,
  instead of distributing the requests evenly.
  

Problem conclusion

Temporary fix

Comments

• The randomization algorithm is improved to more evenly
  distribute group attachment requests.
  
  This PTF also adds a new DB2 subsystem parameter,
  RANDOMATT=YES/NO, which may be specified for each DB2 subsystem
  within the group.  The default setting remains YES, which is
  assumed if no action is taken to update the DB2 subsystem
  parameters.
  
  RANDOMATT=NO may be specified to exclude that member from being
  selected at random.  To satisfy a group attachment request, DB2
  first randomly searches for an active DB2 subsystem, excluding
  those specifying RANDOMATT=NO.  If all such subsystems are
  inactive, DB2 will search for *any* active DB2 subsystem within
  the group, in the order defined by the z/OS subsystem
  initialization, regardless of the setting of RANDOMATT.
  
  To achieve non-randomized group attachments for all members, as
  in DB2 Version 8, specify RANDOMATT=NO for all members of the
  group.
  
  The DSNWZP stored procedure is enhanced to display the current
  value of RANDOMATT in the DB2 subsystem parameter load module.
  
  You may take the following actions after applying this PTF and
  the companion PTF PK79327:
  
      See the ++HOLD actions for required post-apply actions.
  
  (1) Update your DB2 V9 subsystem parameter (DSNZPxxx) module for
      each DB2 subsystem.  (This action is optional if you want to
      continue to use the default setting of RANDOMATT=YES.)  Add
      the keyword parameter
  
         RANDOMATT=NO,
  
      to the invocation of the DSN6GRP macro in your customized
      version of the installation job DSNTIJUZ.  Repeat this for
      each DB2 subsystem within the attachment group.  Make sure
      to add a continuation character in column 72 if needed.  If
      you omit adding RANDOMATT here, the value will be set to the
      default of YES when you assemble the DSNZPxxx module.
  
  (2) Run the first two steps of the DSNTIJUZ job you modified, to
      assemble and link the subsystem parameter load module.
  
  (3) After the job completes, for the change to take affect, you
      must either use the DB2 command -SET SYSPARM for each
      affected DB2 subsystem, or stop and start each affected DB2
      subsystem.  This action is not required if you are using the
      default setting of YES for RANDOMATT.
  
  Additional keywords:  DB2DSHR
  

APAR Information

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

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

  PK79327 UK44898

Modules/Macros

• DSNDGANT DSNDGRP  DSNDQWPZ DSNTIDXA DSNTIJUZ
  DSNTINST DSNWZP   DSN3AMI2 DSN3CHGZ DSN6GRP
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• R910 PSY UK44898

     UP09/04/03 P F904

Fix is available

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