IJ26434: ASSERT EXP(IOBUFFER.NDESC == 1) IN LINE 961, BUFMGR.H

APAR status

• Closed as program error.

Error description

• The EA overflow block is a metadata block
  that should be read using a continuous buffer,
  but due to a code error, it is considered
  to be a data block, so a scatter buffer is used
  which causes a log assert failure.
  

Local fix

• If the size of scatter buffer is bigger than or
  equal to the EA overflow block size, the log
  assert can be avoid.
  Before GPFS version 5.0.0, the default
  scatterBufferSize value is 32KB that is small
  and more likely to hit this log assert.
  Changing the scatterBufferSize value
  to 256KB could be a work around.
  

Problem summary

• The EA overflow block is a metadata block
  that should be read using a continuous buffer,
  but due to a code error, it is considered
  to be a data block, so a scatter buffer is used
  which causes a log assert failure.
  

Problem conclusion

• Benefits of the solution:
  No more log assert
  
  Work Around:
  If the size of scatter buffer is bigger than or
  equal to the EA overflow block size, the log
  assert can be avoid.
  Before GPFS version 5.0.0, the default
  scatterBufferSize value is 32KB that is small
  and more likely to hit this log assert.
  Changing the scatterBufferSize value
  to 256KB could be a work around.
  
  Problem trigger:
  If the file's EA entries cannot be placed in
  the inode, GPFS will place it
  in a per file EA overflow block.
  The size of the EA overflow block depends
  on how many EA entries the file has.
  If the scatterBufferSize value is smaller than
  the EA overflow block size, GPFS may hit
  log assert when the user accesses the file.
  
  Symptom:
  Abend/Crash
  
  Platforms affected:
  ALL Operating System environments
  
  Functional Area affected:
  All Scale Users
  
  Customer Impact:
  High Importance
  

Temporary fix

Comments

APAR Information

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

  IJ26291

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

Fix information

• Fixed component name

  SPEC SCALE STD

• Fixed component ID

  5737F33AP

Applicable component levels