The inspect utility does not report pages that have a bad check
sum. This can be seen in the follow reproduction on Linux.
Patched a data page so that the check sum would fail on reading
the page into memory. Change the value at address 0x50 from 0x0
to 0x8765421.
==> tbd.tsi3.pp24.v101fp3.pre_cksum <==
Page 0000001C
=============
00000000 3000 D00F 0800 0000 0005 002A 0300 0000
0..........*....
00000010 1800 0000 0400 0000 0000 0000 5F03 0000
............_...
00000020 45AA 0300 0000 0000 010F 626B CA77 FAE1
E.........bk.w..
00000030 0100 BB01 0000 0000 FF0D BC01 0000 0000
................
00000040 0000 0000 BD01 0000 0000 0000 0000 0000
................
00000050 0000 0000 0000 0000 0000 0000 0000 0000
................
00000060 *
==> tbd.tsi3.pp24.v101fp3.post_cksum <==
Page 0000001C
=============
00000000 3000 D00F 0800 0000 0005 002A 0300 0000
0..........*....
00000010 1800 0000 0400 0000 0000 0000 5F03 0000
............_...
00000020 45AA 0300 0000 0000 010F 626B CA77 FAE1
E.........bk.w..
00000030 0100 BB01 0000 0000 FF0D BC01 0000 0000
................
00000040 0000 0000 BD01 0000 0000 0000 0000 0000
................
00000050 1234 5678 0000 0000 0000 0000 0000 0000
.4Vx............
00000060 0000 0000 0000 0000 0000 0000 0000 0000
................
Select from the table.
$ db2 "select c1 from tab1"
C1
-----------
1
2
3
4
5
6
7
SQL1655C The operation could not be completed due to an error
accessing data
on disk. SQLSTATE=58030
db2diag.log:
2013-11-06-21.36.22.142089-300 I2048E877 LEVEL:
Severe
PID : 14710 TID : 46912942106944 PROC :
db2sysc
INSTANCE: jsiebran NODE : 000
HOSTNAME: hotel61
EDUID : 118 EDUNAME: db2pfchr (TST)
FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page,
probe:4697
MESSAGE : ZRC=0x86020019=-2046689255=SQLB_CSUM "Bad Page,
Checksum Error"
DIA8426C A invalid page checksum was found for page "".
DATA #1 : String, 27 bytes
CheckSum verification error
DATA #2 : String, 50 bytes
CheckSum values from the page header on disk are :
DATA #3 : unsigned integer, 4 bytes
1801588481
DATA #4 : unsigned integer, 4 bytes
3791288266
DATA #5 : String, 68 bytes
CheckSum values calculated from the page, following the read,
are :
DATA #6 : unsigned integer, 4 bytes
2717563753
DATA #7 : unsigned integer, 4 bytes
3822217694
DATA #6 : Page header, PD_TYPE_SQLB_PAGE_HEAD, 48 bytes
pageHead: {tbspSeed:3;obj:4;type:0} PPNum:24 OPNum:8
begoff: 48
datlen: 4048
pagebinx: 863
revnum: 1280
pagelsn: 000000000003AA45
flag: 2a
future32: 0
cbits1to31: a1fabb69
cbits32to63: e3d269de
Run inspect:
$ db2 inspect check tablespace tbspaceid 3 for error state all
results keep tsi3.fp3.cksum.ins
DB20000I The INSPECT command completed successfully.
DATABASE: TST
VERSION : SQL10012
2013-11-06-21.37.12.659234
Action: CHECK TABLESPACE
Tablespace name: DATA1
Tablespace ID: 3
Result file name: tsi3.fp3.cksum.ins
Table phase start (ID Signed: 4, Unsigned: 4; Tablespace ID:
3) :
Data phase start. Object: 4 Tablespace: 3
Traversing DAT extent map, anchor 12.
Extent map traversal complete.
DAT Object Summary: Total Pages 42 - Used Pages 41 - Free
Space 12 %
Data phase end.
Table phase end.
Tablespace phase end.
Processing has completed. 2013-11-06-21.37.15.937088
db2dart:
Table inspection start: JSIEBRAN.TAB1
Data inspection phase start. Data obj: 4 In pool: 3
Error: CSUM read error for pool page 24, from object ID
4, pool 3,
Error: BPS Tail incorrect CBITS value -- (a)
Error: in page 8, pool page 24, of Object 4, in
tablespace 3.
Error: CSUM read error for pool page 24, from object ID
4, pool 3,
Error: Page data will be dumped to report.
Error: This phase encountered an error and did not
complete.
Data inspection phase end.
Table inspection end.
As can be seen inspect does not report any error for the page
with the bad check sum. This is also reproducible on V10.5 as
well |
After running the inspect utility investigate the db2diag.log
for any entries that identify pages with a bad check sum as
below:
2013-11-06-20.50.16.182573-300 I1702E877 LEVEL:
Severe
PID : 6493 TID : 46912937912640 PROC :
db2sysc
INSTANCE: jsiebran NODE : 000
HOSTNAME: hotel61
EDUID : 487 EDUNAME: db2pfchr (TST)
FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page,
probe:4697
MESSAGE : ZRC=0x86020019=-2046689255=SQLB_CSUM "Bad Page,
Checksum Error"
DIA8426C A invalid page checksum was found for page
"".
DATA #1 : String, 27 bytes
CheckSum verification error
DATA #2 : String, 50 bytes
CheckSum values from the page header on disk are :
DATA #3 : unsigned integer, 4 bytes
2035944898
DATA #4 : unsigned integer, 4 bytes
3791288261
DATA #5 : String, 68 bytes
CheckSum values calculated from the page, following the read,
are :
DATA #6 : unsigned integer, 4 bytes
2951920170
DATA #7 : unsigned integer, 4 bytes
3822217689
2013-11-06-20.50.16.320194-300 I2580E3899 LEVEL:
Severe
PID : 6493 TID : 46912937912640 PROC :
db2sysc
INSTANCE: jsiebran NODE : 000
HOSTNAME: hotel61
EDUID : 487 EDUNAME: db2pfchr (TST)
FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page,
probe:0
MESSAGE : ZRC=0x86020019=-2046689255=SQLB_CSUM "Bad Page,
Checksum Error"
DIA8426C A invalid page checksum was found for page
"".
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
24
DATA #4 : Object descriptor, PD_TYPE_SQLB_OBJECT_DESC, 96 bytes
Obj: {pool:3;obj:4;type:0} Parent={3;4}
lifeLSN: 000000000003A881 |
