LI72053: SNAPSHOT MONITOR UDFS RUN LONGER WHEN MONITOR STREAM EXCEEDS PREDEFINED BUFFER SIZE

DB2 Version 9.1 Fix Pack 7  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 5   for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 6   for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 6a for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 7a  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 8  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 9  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 10  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 11  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 12  for Linux, UNIX and Windows

APAR status

• Closed as program error.

Error description

• The Snapshot UDFs (i.e. SNAPSHOT_APPL_INFO) run longer when the
  monitor stream is too large causing to not fit in a fixed memory
  buffer thus causing it to spill to disk.  This results in DB2
  having to read from a file.
  
  The fixed buffer is controlled internally by a parameter
  MAX_SNAP_SZ and this APAR will allow this buffer to be
  controllable by the user to support larger monitor streams to
  fit in the buffer.
  
  You are vulnerable to this problem if when you run the snapshot
  (i.e. select from TABLE(SNAPSHOT_APPL_INFO) and take a db2trc
  with timestamp option and then examine the trace flow
  you will see calls to seek into a file inbetween calls to the
  snapshot functions.
  
  For example, the trace flow below shows the snapshot took 18
  seconds and in that same time, the reads to the file also took
  18 seconds (i.e. 48 - 30)
  
  514182        30:273710000   | | | snapshot_appl_info entry
  ending
  933541        48:847414000   | | | snapshot_appl_info exit
  
  With the file reads taking the majority of the time
  645695        30:770411000   | | | | | | | | OSSHFile::open
  entry
  ending
  933146        48:579336000   | | | | | | | | OSSHFile::read exit
  

Local fix

Problem summary

• see problem description
  

Problem conclusion

• First Fixed in DB2 version 9.1 fixpak 5
  

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:

  LI72054

Fix information

• Fixed component name

  DB2 UDE ESE LIN

• Fixed component ID

  5765F4104

Applicable component levels

• R910 PSY

     UP