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DB2 - Problem description

Problem IC85699 Status: Closed

BAD PAGE OR READ ERROR FOLLOWING UNDO PROCESSING OF "CREATE
TABLE" LOG RECORD FOR TABLE CONTAINING LOB OBJECT

product:
DB2 FOR LUW / DB2FORLUW / 970 - DB2
Problem description:
When undoing (rolling back) a "CREATE TABLE" log record 
(UNDOCREATE_OBJECT_DP) for a table containing a LOB object (e.g. 
during crash recovery, rollforward, or HADR Standby processing), 
a stale value of the extent anchor for the table may be left in 
memory. Simplified, an extent anchor is the pointer to the first 
extent used by the table. 
 
If this is followed by an operation that requires the extent 
anchor, for example extent movement, and the database has not 
been restarted prior to this, the stale value will cause DB2 to 
access an incorrect page pointed to by the stale extent anchor. 
This will result in errors such as SQLB_BADHDR or SQLB_READERR. 
 
So far the problem has been seen during extent movement. The 
typical call stack contains: 
 
sqlbScanAllEMPsForObject 
sqlbFindEMPMappingMovedExtent 
sqlbMoveHighestExtent 
sqlbLockAndMoveExtents 
sqlbExtentMovementEntryPoint 
 
db2diag.log example showing a request to read a page from 
pool:4;obj:4100, whereas a page from tbspSeed:4;obj:279 was 
retrieved: 
 
2012-02-25-07.41.35.182980-300 I233648186E4455       LEVEL: 
Severe 
PID     : 28199                TID : 140497825818368 PROC : 
db2sysc 
INSTANCE: db2inst1             NODE : 000            DB   : 
SAMPLE 
APPHDL  : 0-62840              APPID: *LOCAL.DB2.120225124901 
AUTHID  : DB2INST1             HOSTNAME: localhost 
EDUID   : 6474                 EDUNAME: db2agent (SAMPLE) 
FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page, 
probe:14 
MESSAGE : ZRC=0x87020036=-2029912010=SQLB_BADHDR "Bad Page 
Header" 
          DIA8547C An error occurred in a database page header. 
DATA #1 : String, 64 bytes 
Error encountered trying to read a page - information follows : 
DATA #2 : String, 23 bytes 
Page verification error 
DATA #3 : Page ID, PD_TYPE_SQLB_PAGE_ID, 4 bytes 
9416 
DATA #4 : Object descriptor, PD_TYPE_SQLB_OBJECT_DESC, 96 bytes 
    Obj: {pool:4;obj:4100;type:67} Parent={4;4100} 
 
<...skipping...> 
 
DATA #6 : Page header, PD_TYPE_SQLB_PAGE_HEAD, 48 bytes 
pageHead: {tbspSeed:4;obj:279;type:0} PPNum:9416 OPNum:16 
 
<...skipping...> 
 
CALLSTCK: (Static functions may not be resolved correctly, as 
they are resolved to the nearest symbol) 
 [0] 0x00007FC8E07FB33E pdLog + 0x38E 
 [1] 0x00007FC8E206E801 sqlbLogReadAttemptFailure + 0x1E1 
 [2] 0x00007FC8E38C1B53 sqlbReadPage + 0xE13 
 [3] 0x00007FC8E38B7716 sqlbGetPageFromDisk + 0x5C6 
 [4] 0x00007FC8E389AA3F sqlbfix + 0x112F 
 [5] 0x00007FC8E079E2D7 sqlbFixPage + 0x17 
 [6] 0x00007FC8E20429D0 /home/svtdbm12/sqllib/lib64/libdb2e.so.1 
+ 0x27619D0 
 [7] 0x00007FC8E204428A sqlbScanAllEMPsForObject + 0x2AA 
 [8] 0x00007FC8E2045408 sqlbFindEMPMappingMovedExtent + 0xA28 
 [9] 0x00007FC8E204639C sqlbMoveHighestExtent + 0x9EC 
[10] 0x00007FC8E2048C69 sqlbLockAndMoveExtents + 0xEB9 
[11] 0x00007FC8E2049C6C sqlbExtentMovementEntryPoint + 0xAC 
[12] 0x00007FC8E0AC31CA sqleIndCoordProcessRequest + 0x7FA 
[13] 0x00007FC8E0AD4556 sqeAgent::RunEDU + 0x2B6 
[14] 0x00007FC8E1AD4A83 sqzEDUObj::EDUDriver + 0xF3 
[15] 0x00007FC8E1AD4989 sqlzRunEDUP + 0x9 
[16] 0x00007FC8E1562FEF sqloEDUEntry + 0x29F 
[17] 0x00007FC8E6D465F0 /lib64/libpthread.so.0 + 0x75F0 
[18] 0x00007FC8DE7C884D clone + 0x6D
Problem Summary:
**************************************************************** 
* USERS AFFECTED:                                              * 
* See APAR Description                                         * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 for Linux, UNIX, and Windows 9.7 Fix Pack 7.  * 
****************************************************************
Local Fix:
Restart (deactivate and activate) the database, which will 
refresh the stale extent anchor value.
available fix packs:
DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows

Solution
Problem first fixed in DB2 for Linux, UNIX, and Windows 9.7 Fix 
Pack 7.
Workaround
not known / see Local fix
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
02.08.2012
20.10.2012
20.10.2012
Problem solved at the following versions (IBM BugInfos)
9.7.,
9.7.FP7
Problem solved according to the fixlist(s) of the following version(s)
9.7.0.7 FixList
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