DB2 FOR LUW / DB2FORLUW / A10 - DB2

DB2 does not make use of "Vectored IO" when a table space has 
only one container. Applying the APAR makes it possible to take 
advantage of "Vectored IO" even if a table space has only one 
container. 
 
One of the benefits of using "Vectored IO" is: it may possibly 
avoid one ONLINE BACKUP performance issue that happens in 
pureScale environment only. 
When the performance issue is happening, following information 
can be observed in stack files of DB2 prefetchers (EDU name 
'db2pfchr'): 
=========================================== 
<StackTrace> 
thread_wait 
getConflictComplex 
getConflict 
get 
sqlbDMSDirectRead 
sqlbDirectRead 
sqlbServiceDirectReadRequest 
sqlbPFPrefetcherEntryPoint 
</StackTrace> 
 
<LatchInformation> 
Waiting on latch type: (SQLO_LT_SQLB_POOL_CB__olbRangeLotch) 
</LatchInformation> 
=========================================== 
The ONLINE BACKUP is slow because multiple prefetchers are 
competing for the 'SQLO_LT_SQLB_POOL_CB__olbRangeLotch'. 
When prefetchers are making use of "Vectored IO", there is no 
competition for the latch hence the performance issue is 
avoided.

**************************************************************** 
* USERS AFFECTED:                                              * 
* All users of version 10.1 on Linux, Unix and Windows         * 
* platforms.                                                   * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Update to DB2 LUW Version 10.1 Fix Pack 4 or higher levels.  * 
****************************************************************

Change table spaces from "one container" to "multiple 
containers".

DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows
 

First fixed in DB2 LUW Version 10.1 Fix Pack 4.

Change table spaces from "one container" to "multiple 
containers".

forerunner  : APAR is sysrouted TO one or more of the following: IC96714 
follow-up : 

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

29.09.2013
09.06.2014
09.06.2014