|
Problem IC96714
|
Status: Closed |
TABLE SPACES HAVING ONLY ONE CONTAINER CAN NOT MAKE USE OF "VECTORED IO" |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
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. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All users of version 10.5 on Linux, Unix and Windows *
* platforms. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Update to DB2 LUW Version 10.5 Fix Pack 4 or higher levels. *
**************************************************************** |
| Local Fix: |
Change table spaces from "one container" to "multiple
containers". |
| available fix packs: |
DB2 Cancun Release 10.5.0.4 (also known as Fix Pack 4) for Linux, UNIX, and Windows
DB2 Version 10.5 Fix Pack 9 for Linux, UNIX, and Windows
|
| Solution |
First fixed in DB2 LUW Version 10.5 Fix Pack 4. |
| Workaround |
Change table spaces from "one container" to "multiple
containers". |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 08.10.2013
26.08.2014
26.08.2014 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.4
|
 |
