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DB2 - Problem description

Problem IC83352 Status: Closed

BAD PAGE HEADER ENCOUNTERED BY PREFETCHER DURING ONLINE BACKUP ON LINUX
PLATFORM. BACKUP IMAGE MAY BE CORRUPTED.

product:
DB2 FOR LUW / DB2FORLUW / 980 - DB2
Problem description:
This problem exists on the Linux platform only. 
 
 
Conditions through which the Bad Page Header is encountered: 
 
1)  Linux operating system 
2)  DB2 V9.8 
3)  Tablespaces with multiple containers 
4)  Online backup 
5)  Significant user activity which drives prefetching during 
online backup 
 
 
There are 2 possible consequences: 
 
1)  Incorrect pages are silently written to the online backup. 
Any restore from this backup image will result in data 
corruption. 
2)  Bad Page Header messages encountered by prefetchers during 
the online backup. 
 
 
2011-06-01-21.04.29.871752-240 I495774E3614        LEVEL: Severe 
PID    : 11263                TID  : 47129540159808PROC : 
db2sysc 
INSTANCE: db2inst1        NODE : 000 
EDUID  : 134                  EDUNAME: db2pfchr (SAMPLE) 
FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page, 
probe:13 
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 
9678 
DATA #4 : Object descriptor, PD_TYPE_SQLB_OBJECT_DESC, 88 bytes 
    Obj: {pool:4;obj:4;type:1} Parent={4;4} 
  lifeLSN:      0000000010F75884 
  tid:          0 0  0 
  extentAnchor:                8490 
  initEmpPages:                  0 
  poolPage0:                      0 
  poolflags:                  3122 
  objectState:                  27 
  lastSMP:                        0 
  pageSize:                  16384 
  extentSize:                    2 
  bufferPoolID:                  2 
  partialHash:            17039364 
  bufferPool:    0x00002adc27f347c0 
  pdef:          0x00002adc2de8aec0 
DATA #5 : Bitmask, 4 bytes 
0x00000002 
DATA #6 : Page header, PD_TYPE_SQLB_PAGE_HEAD, 48 bytes 
pageHead: {tbspSeed:4;obj:4;type:0} PPNum:2770 OPNum:2762 
  begoff:                      48 
  datlen:                  16336 
  pagebinx:                    0 
  revnum:                    1280 
  pagelsn:    000000000238ED4C  flag:                        2 
  future32:                    0 
  cbits1to31:            1c02807 
  cbits32to63:                  0 
 
CALLSTCK: 
  [0] 0x00002ADBBF2955A2 pdLog + 0x398 
  [1] 0x00002ADBBFF73186 
_Z25sqlbLogReadAttemptFailurejP16SQLB_OBJECT_DESCjP9SQLB_PAGEibm 
jPcP12SQLB_GLOBALS 
+ 0x1BE 
  [2] 0x00002ADBC1A59352 
_Z16sqlb_verify_pageP9SQLB_PAGEP16SQLB_OBJECT_DESCjjP12SQLB_GLOB 
ALSPm 
+ 0x376 
  [3] 0x00002ADBBF2CDFF8 
_Z25sqlbReadAndReleaseBuffersP16SQLB_OBJECT_DESCjmmmP11SQLB_pfMi 
sc 
+ 0x984 
  [4] 0x00002ADBBF2CC538 
_Z16sqlbProcessRangeP16SQLB_OBJECT_DESCjjP11SQLB_pfMisc + 0x140 
  [5] 0x00002ADBBF2CB7B7 
_Z26sqlbPFPrefetcherEntryPointP16sqbPrefetcherEdu + 0x3C9 
  [6] 0x00002ADBBF2CB3AD _ZN16sqbPrefetcherEdu6RunEDUEv + 0x2F 
  [7] 0x00002ADBBFA9732C _ZN9sqzEDUObj9EDUDriverEv + 0xA6 
  [8] 0x00002ADBBFA97283 _Z10sqlzRunEDUPcj + 0x9 
  [9] 0x00002ADBBF80B3D2 sqloEDUEntry + 0x2F4 
 
 
The db2diag.log entries in the above example show that DB2 
requested page 9678 from tablespace 4, but received page 2770 
from tablespace 4. In order to verify the occurrence of the bad 
page header issue, the received page must be in the same 
tablespace as the requested page.
Problem Summary:
**************************************************************** 
* USERS AFFECTED:                                              * 
* DB2 V9.8 pureScale on Linux                                  * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to V98 Fixpack 5                                     * 
****************************************************************
Local Fix:
For the following command: 
 
db2set DB2BPVARS=<file> 
 
Replace <file> with a fully qualified file name, such 
as /home/db2inst1/bpvars.cfg 
 
Place the following line in the stated file: 
 
NOREADVBCKUP=1 
 
Restart DB2 to propagate changes.
Solution
See Error Description
Workaround
not known / see Local fix
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
11.05.2012
21.06.2012
01.07.2012
Problem solved at the following versions (IBM BugInfos)
9.8.FP5
Problem solved according to the fixlist(s) of the following version(s)
9.8.0.5 FixList