LI73318: DATA CORRUPTION WHEN A LOB OBJECT ASSOCIATED WITH A TABLE GROWS LARGER THAN 2 TB

DB2 Version 9.5 Fix Pack 3b for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 2a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 2  for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 4  for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 4a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 5 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 6a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 10 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• When a large object (BLOB, CLOB, or DBCLOB data type) object
  that is associated with a table crosses the 2 terabyte (TB) size
  boundary, there is a problem in the space allocation algorithm
  that can lead to corruption of the table space.  For example a
  previously allocated extent might be erroneously reused.  One
  occurrence of this problem resulted in the beginning pages of
  the LOB table space being overwritten when the LOB object grew
  larger than 2 terabytes.
  

Local fix

• Use a range partitioned table to split LOBs for a column into
  separate LOB objects to avoid crossing the 2TB threshold for a
  single LOB object.
  
  The size of the LOB object can be determined using the following
  command:
  
  db2pd -db dbname -tcbstats
  
  One of the columns that is generated in this report is LobSize
  (which is shown as number of pages).  A quick calculation
  (number of pages * page size) will give the size of the LOB
  object.
  
  If the LOB object has already crossed the 2TB boundary just
  applying the fix will not correct the issue, the table will
  still need to be rebuilt.
  

Problem summary

• Problem Description: a LOB object that grows larger than 2TB can
  become corrupt
  Problem Summary: see above
  Users Affected: Any with large LOB objects associated with a
  table.
  

Problem conclusion

• Problem was first fixed in Version 9.5 FixPak 2
  

Temporary fix

• n/a
  

Comments

APAR Information

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

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

  LI73319

Fix information

• Fixed component name

  DB2 UDB WSE LIN

• Fixed component ID

  5765F3504

Applicable component levels

• R810 PSN

     UP

• R820 PSN

     UP