DB2 FOR LUW / DB2FORLUW / 950 - DB2

SOLARIS 10 UPDATE 4 includes an enhancement - multiple page size 
support for pagable shared memory - which impacts DB2. 
Solaris will choose the largest page size appropriate for 
pagable shared memory allocations. 
DB2 takes advantage of this for Automatic Database Shared 
Memory, but uses a maximum 64K page size (this is documented). 
This maximum page size is required as DB2 decommits memory in 
multiples of 64K. 
 
This APAR will address the Application Memory area which 
currently uses the default page size chosen by Solaris. 
This memory area also grows and shrinks (is decommited) in 
multiples of 64K. 
Given the typical sizes of Application Memory shared 
allocations, Solaris will choose a page size of 4MB. 
Whenever DB2 decommits a portion of the large page, the entire 
page may be reused for other purposes on the system. 
This could result in perceived memory corruption and a DB2 
instance crash, since DB2 is still expecting other ranges on the 
large page to be valid. 
However, the nature of the decommit operation on Solaris is such 
that if DB2 references memory on the page before it is 
reassigned, the memory page returns to it's previous state and 
the ranges continue to be valid. 
Given that all of  "in-use" Application Memory is continually 
accessed, it would be extremely rare for the memory page to be 
reused by the operating system, and this problem has not been 
seen by customers. 
 
The APAR is resolved by changing Application Memory to use a 
maximum 64K pagesize on Solaris, similar to AUTOMATIC Database 
Memory.

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* USERS AFFECTED:                                              * 
* DB2 systems running on Solaris                               * 
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* PROBLEM DESCRIPTION:                                         * 
* See error description                                        * 
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* RECOMMENDATION:                                              * 
* Upgrade to DB2 level containing APAR                         * 
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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
 

Problem first fixed in DB2 Version 9.5 Fix Pack 6

not known / see Local fix

forerunner  : APAR is sysrouted TO one or more of the following: IC65171 
follow-up : 

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

16.12.2009
22.06.2010
22.06.2010

9.5.FP6