DB2 FOR LUW / DB2FORLUW / A10 - DB2

DB2's strategy for LONG/LOB writes may cause an apparent 
slowdown in I/O within DB2 (not at the operating system level). 
This is because contention may occur in DB2's internal file 
management when file sync operations are performed at commit 
time.  This strategy is followed during heavier LONG/LOB write 
activity where LONG/LOB writes may become buffered (not written 
immediately to disk).  On systems where LONG/LOB data is stored 
in tablespaces with NO FILE SYSTEM CACHING (direct I/O), there 
is no advantage in this strategy as the writes will not be 
buffered. 
 
If long wait times on the 
SQLO_LT_SqlbFhdlHashEntry__hashEntryLatch latch can be observed 
via the MON_GET_EXTENDED_LATCH_WAIT monitoring routine, consider 
disabling this behavior as follows : 
 
   db2set DB2_BUFFER_LONG_DATA_WRITES=OFF 
 
This takes effect when the database is deactivated/activated. 
 
Example: 
db2 "select total_extended_latch_wait_time from 
table(mon_get_extended_latch_wait(null)) where 
LATCH_NAME='SQLO_LT_SqlbFhdlHash 
Entry__hashEntryLatch'"

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* USERS AFFECTED:                                              * 
* DB2/Systems with heavy LOB I/O                               * 
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* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* Upgrade to DB2 Version 10.1 Fix Pack 5                       * 
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If long wait times are observed on the 
SQLO_LT_SqlbFhdlHashEntry__hashEntryLatch latch are observed, 
disable buffered LONG/LOB writes with db2set 
DB2_BUFFER_LONG_DATA_WRITES=OFF  (the database must be recycled)

Problem first fixed in DB2 Version 10.1 Fix Pack 5

see Local Fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

23.10.2014
23.07.2015
23.07.2015