PI12512: BPOOL STORAGE CALCULATION CHANGE IF PGFIX=Y WITH 1MB FRAMES & VPSIZE IS SMALL (LESS THAN 6656), ALLOW 1MB FIXED STG ALLOCATION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When 1MB is allocated for the control blocks, these control
  blocks can cover 6656 buffers in the buffer pool.  For a small
  buffer pool (VPSIZE is less than 6656), DB2 allocates buffers
  using 4K frames to avoid wasting 1MB fixed storage.  Storage
  calculation will be adjusted to allow  1MB fixed storage
  allocation for  VPSIZE  that is less than  6656.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 users.                               *
  ****************************************************************
  * PROBLEM DESCRIPTION: For a small PGFIX=YES buffer pool with  *
  *                      VPSIZE less than 6656, DB2 allocates    *
  *                      page buffers using 4K frames.           *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  DB2 uses control blocks to track page buffers in a buffer pool.
  These control blocks are allocated on a 1MB boundary and 1MB
  of control blocks can cover 6656 page buffers. To maximize the
  use of control blocks and avoid waste of fixed storage, DB2
  only allocates fixed storage for a PGFIX=YES buffer pool if
  VPSIZE is 6656 or greater.
  

Problem conclusion

• DB2 has enhanced buffer pool allocation logic to use fixed
  storage for a PGFIX=YES buffer pool when the buffer storage is
  at least 1MB. For example, for a 4K buffer pool to use
  1MB fixed storage, the VPSIZE needs to be at least 256.
  

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:

  UI17304

Modules/Macros

• DSNB1ABS
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UI17304

     UP14/05/09 P F405 ½

Fix is available

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