DB2 FOR LUW / DB2FORLUW / B10 - DB2

While the excess memory will not be referenced and not backed by 
memory or paging space/swap during normal operations, the 
virtual allocation amount may still cause some problematic 
symptoms. 
 
1. unexpected memory allocation errors on Linux if the shmall 
limit is reached (maximum allowed virtual shared memory 
allocation on the system).  This is more likely on 
multi-instance systems where the INSTANCE_MEMORY setting is 
AUTOMATIC (each instance will create an FMP memory segment 
roughly 50% * RAM) 
2. excessive coredump file sizes 
3. on AIX, if there is a DB2 crash/trap, the large virtual 
allocation becomes committed as a coredump is written out.  This 
may lead to a much longer outage due to paging, and eventually a 
system-level hang or crash as paging space becomes exhausted. 
 
Note there is a distinct problem symptom documented in APAR 
IT19442 that is also caused by the large FMP shared memory 
allocation.  Restricting the allocation size as per the Local 
Fix will also address that problem symptom.

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* USERS AFFECTED:                                              * 
* All users are affected                                       * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* use workaround in "Local Fix"                                * 
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Set the FMP memory segment size to the original 256MB amount 
   db2set DB2NTMEMSIZE=APLD:268435456 
This requires recycling the instance (db2stop force; db2start) 
 
While the documentation indicates that DB2NTMEMSIZE is valid 
only for the Windows platform, it is also effective for UNIX 
platforms on the DB2 level vulnerable to this APAR (DB2 v11.1 
mod 1 fix pack 1).  Its use is not generally supported on UNIX 
platforms, and the setting should be removed upon upgrading to a 
level containing the APAR fix.

DB2 Version 11.1 Mod 2 Fix Pack 2 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod2 Fix Pack2 iFix001 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod2 Fix Pack2 iFix002 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod 3 Fix Pack 3 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod3 Fix Pack3 iFix001 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod3 Fix Pack3 iFix002 for Linux, UNIX, and Windows
 

Projected: Problem first fixed in DB2 Version 11.1 mod 2 fix 
pack 1

see Local Fix

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

28.02.2017
23.06.2017
23.06.2017