Latest versionsfixlist
11.1.0.7 FixList
10.5.0.9 FixList
10.1.0.6 FixList
9.8.0.5 FixList
9.7.0.11 FixList
9.5.0.10 FixList
9.1.0.12 FixList
Have problems? - contact us.
Register for free anmeldung-x26
Contact form kontakt-x26

DB2 - Problem description

Problem IC70147 Status: Closed

HWM TOO LOW DUE TO TIMING WINDOW WHEN NEW SMP EXTENT ALLOCATED, CAN LEAD TO
DATA CORRUPTION

product:
DB2 FOR LUW / DB2FORLUW / 970 - DB2
Problem description:
There is a very small timing window where we cache the value of 
the last initialized SMP extent. 
We then use this value to calculate the high-water mark. 
If a new SMP extent gets allocated within that timing window 
then we'll set the high-water mark to a value that is too low. 
 
Various operations will result in this subsequently getting set 
correctly, but it is possible for a tablespace reduce to occur 
and we can get rid of extents after the high-water mark... 
extents that are in use by the tablespace. 
This results in data corruption. 
 
When this happens one of the symptoms is at database start up 
time 
the tablespace will be put to OFFLINE state and the following 
error 
will appear in the db2diag.log: 
 
2010-07-09-04.39.06.621170+120 I420281399A2620    LEVEL: Severe 
PID     : 10563                TID  : 27          PROC : db2sysc 
0 
INSTANCE: db2               NODE : 000         DB   : SAMPLE 
APPHDL  : 0-973                APPID: *LOCAL.db2pc1.100709023906 
AUTHID  : DB2 
EDUID   : 27                   EDUNAME: db2agent (SAMPLE) 0 
FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page, 
probe:3 
MESSAGE : ZRC=0x86020001=-2046689279=SQLB_BADP "page is bad" 
          DIA8400C A bad page was encountered. 
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 
11776007 
DATA #4 : Object descriptor, PD_TYPE_SQLB_OBJECT_DESC, 72 bytes 
    Obj: {pool:9;obj:65534;type:14} Parent={9;65534} 
  lifeLSN:       000000000000 
  tid:           0 0  0 
  extentAnchor:                   0 
  initEmpPages:                   0 
  poolPage0:                      0 
  poolflags:                   2122 
  objectState:                    0 
  lastSMP:                        0 
  pageSize:                    4096 
  extentSize:                     8 
  bufferPoolID:                   1 
  partialHash:           4059955209 
  bufferPool:    0x7ffffff9b713bb40 
DATA #5 : Bitmask, 4 bytes 
0x00000002 
DATA #6 : Page header, PD_TYPE_SQLB_PAGE_HEAD, 48 bytes 
pageHead: {pool:0;obj:0;type:0} PPNum:0 OPNum:0 
  begoff:                       0 
  datlen:                       0 
  pagebinx:                     0 
  revnum:                       0 
  pagelsn:     000000000000  flag:                         0 
  signature:                    0 
  cbits1to31:                   0 
  cbits32to63:                  0 
CALLSTCK: 
  [0] 0x7FFFFFFF7B017F30 
__1cZsqlbLogReadAttemptFailure6FIpnQSQdDLB_OBJECT_DESC_IpnJSQdDL 
B_PAGE_ibLIpcpnMSQdDLB_GLOBALS__v_ 
+ 0x150 
  [1] 0x7FFFFFFF7B01C8B8 
__1cQsqlb_verify_page6FpnJSQdDLB_PAGE_pnQSQdDLB_OBJECT_DESC_IIpn 
MSQdDLB_GLOBALS_pL_i_ 
+ 0x598 
  [2] 0x7FFFFFFF7B01965C sqlbReadPage + 0xE84 
  [3] 0x7FFFFFFF7AFF9334 
__1cTsqlbGetPageFromDisk6FpnLSQdDLB_FIX_CB_i_i_ + 0x2EC 
  [4] 0x7FFFFFFF7AF42404 __1cHsqlbfix6FpnLSQdDLB_FIX_CB__i_ + 
0xA1C 
  [5] 0x7FFFFFFF7B07AFA0 
__1cYsqlbFindNewHighWaterMark6FHIpnJSQdDLP_LSN8_LpnMSQdDLB_GLOBA 
LS__i_ 
+ 0xC38 
  [6] 0x7FFFFFFF7B06F4F8 
__1cQsqlbDMSStartPool6FpnMSQdDLB_GLOBALS_pnMSQdDLB_POOL_CB__i_ + 
0x7B8 
 
 
Another possible symptom is some objects in the tablespace will 
have data beyond the 
high water mark, resulting in data corruption in the objects. 
Though the problem may 
remain undetected until the object is accessed, running db2dart 
/TS on the tablespace 
will catch this.
Problem Summary:
**************************************************************** 
* USERS AFFECTED:                                              * 
* ALL                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* HWM TOO LOW DUE TO TIMING WINDOW WHEN NEW SMP                * 
* EXTENTALLOCATED, CAN LEAD TO DATA CORRUPTIONThere is a very  * 
* small timing window where we cache the valueofthe last       * 
* initialized SMP extent.We then use this value to calculate   * 
* the high-water mark.If a new SMP extent gets allocated       * 
* within that timing windowthen we'll set the high-water mark  * 
* to a value that is toolow.Various operations will result in  * 
* this subsequently gettingsetcorrectly, but it is possible    * 
* for a tablespace reduce tooccurand we can get rid of extents * 
* after the high-water mark...extents that are in use by the   * 
* tablespace.This results in data corruption.When this happens * 
* one of the symptoms is at database startuptimethe tablespace * 
* will be put to OFFLINE state and thefollowingerrorwill       * 
* appear in the db2diag.log:2010-07-09-04.39.06.621170+120     * 
* I420281399A2620    LEVEL:SeverePID    : 10563                * 
* TID  : 27          PROC :db2sysc0INSTANCE: db2               * 
* NODE : 000        DB  : SAMPLEAPPHDL  : 0-973                * 
* APPID:*LOCAL.db2pc1.100709023906AUTHID  : DB2EDUID  : 27     * 
* EDUNAME: db2agent (SAMPLE) 0FUNCTION: DB2 UDB,               * 
* buffer pool services, sqlb_verify_page,probe:3MESSAGE :      * 
* ZRC=0x86020001=-2046689279=SQLB_BADP "page is bad"DIA8400C A * 
* bad page was encountered.DATA #1 : String, 64 bytesError     * 
* encountered trying to read a page - informationfollows :DATA * 
* #2 : String, 23 bytesPage verification errorDATA #3 : Page   * 
* ID, PD_TYPE_SQLB_PAGE_ID, 4 bytes11776007DATA #4 : Object    * 
* descriptor, PD_TYPE_SQLB_OBJECT_DESC, 72bytesObj:            * 
* {pool:9;obj:65534;type:14} Parent={9;65534}lifeLSN:          * 
* 000000000000tid:          0 0  0extentAnchor:                * 
* 0initEmpPages:                  0poolPage0:                  * 
* 0poolflags:                  2122objectState:                * 
* 0lastSMP:                        0pageSize:                  * 
* 4096extentSize:                                              * 
* 8bufferPoolID:                  1partialHash:                * 
* 4059955209bufferPool:    0x7ffffff9b713bb40DATA #5 :         * 
* Bitmask, 4 bytes0x00000002DATA #6 : Page header,             * 
* PD_TYPE_SQLB_PAGE_HEAD, 48 bytespageHead:                    * 
* {pool:0;obj:0;type:0} PPNum:0 OPNum:0begoff:                 * 
* 0datlen:                      0pagebinx:                     * 
* 0revnum:                      0pagelsn:    000000000000      * 
* flag:                        0signature:                     * 
* 0cbits1to31:                  0cbits32to63:                  * 
* 0CALLSTCK:[0]                                                * 
* 0x7FFFFFFF7B017F30__1cZsqlbLogReadAttemptFailure6FIpnQSQdDLB_O 
* 0x150[1]                                                     * 
* 0x7FFFFFFF7B01C8B8__1cQsqlb_verify_page6FpnJSQdDLB_PAGE_pnQSQd 
* 0x598[2] 0x7FFFFFFF7B01965C sqlbReadPage + 0xE84[3]          * 
* 0x7FFFFFFF7AFF9334__1cTsqlbGetPageFromDisk6FpnLSQdDLB_FIX_CB_i 
* + 0x2EC[4] 0x7FFFFFFF7AF42404                                * 
* __1cHsqlbfix6FpnLSQdDLB_FIX_CB__i_+0xA1C[5]                  * 
* 0x7FFFFFFF7B07AFA0__1cYsqlbFindNewHighWaterMark6FHIpnJSQdDLP_L 
* 0xC38[6]                                                     * 
* 0x7FFFFFFF7B06F4F8__1cQsqlbDMSStartPool6FpnMSQdDLB_GLOBALS_pnM 
* possible symptom is some objects in the tablespacewillhave   * 
* data beyond thehigh water mark, resulting in data corruption * 
* in theobjects.Though the problem mayremain undetected until  * 
* the object is accessed, runningdb2dart/TS on the             * 
* tablespacewill catch this.                                   * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 version 9.7 and Fix Pack 3                    * 
****************************************************************
Local Fix:
Contact service when the above occurs.
available fix packs:
DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
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 was first fixed in DB2 version 9.7 and Fix Pack 3
Workaround
not known / see Local fix
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
23.07.2010
24.09.2010
24.09.2010
Problem solved at the following versions (IBM BugInfos)
9.7.
Problem solved according to the fixlist(s) of the following version(s)
9.7.0.3 FixList
9.7.0.3 FixList
This site uses cookies to make it easier for us to provide you with our services. By using our site you agree to the use of cookies.