月归档：九月 2011

DUMPING ORACLE BLOCKS

发表于 2011 年 9 月 17 日 由 惜分飞

我见识过的，讲的最好的关于dump相关的文章，这个里面关于dump block,dump index,dump controlfile说的比较详细，看了收获不小，现在贡献出来和大家分享
如何阅读oracle数据块的dump文件
//files.xifenfei.com/wp-content/uploads/2011/09/read_oracle_dump.pdf

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假坏块引起恐慌

发表于 2011 年 9 月 16 日 由 惜分飞

alert文件出现如下日志
Fri Sep 16 02:58:25 2011
Hex dump of (file 19, block 1444767) in trace file /opt/oracle/admin/ora9i/udump/ora9i_ora_24702.trc
Corrupt block relative dba: 0x04d60b9f (file 19, block 1444767)
Fractured block found during backing up datafile
Data in bad block:
type: 6 format: 2 rdba: 0x04d60b9f
last change scn: 0x0abf.56961827 seq: 0×1 flg: 0×04
spare1: 0×0 spare2: 0×0 spare3: 0×0
consistency value in tail: 0x7c340601
check value in block header: 0xba17
computed block checksum: 0×6413
Reread of blocknum=1444767, file=/opt/oracle/oradata/ora9i/TS_INDX_Base.005.dbf. found valid data

因为这个是我们比较重要的业务服务器，如果出现坏块，不能及时处理，后果将不堪设想，因此我马上检查

先查看是什么对象：(结果是一个分区表的index，担心减少一半，index大不了重建，无大事)

SELECT OWNER, SEGMENT_NAME, SEGMENT_TYPE, TABLESPACE_NAME, A.PARTITION_NAME
  FROM DBA_EXTENTS A
 WHERE FILE_ID = &FILE_ID
   AND &BLOCK_ID BETWEEN BLOCK_ID AND BLOCK_ID + BLOCKS - 1;

然后检查是否真的坏块
方法一：dbv

[oracle@DB1 bdump]$ dbv file=/opt/oracle/oradata/ora9i/TS_INDX_Base.005.dbf blocksize=8192

DBVERIFY: Release 10.2.0.4.0 - Production on Fri Sep 16 09:15:11 2011

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

DBVERIFY - Verification starting : FILE = /opt/oracle/oradata/ora9i/TS_INDX_Base.005.dbf


DBVERIFY - Verification complete

Total Pages Examined         : 2207744
Total Pages Processed (Data) : 0
Total Pages Failing   (Data) : 0
Total Pages Processed (Index): 2201581
Total Pages Failing   (Index): 0
Total Pages Processed (Other): 3271
Total Pages Processed (Seg)  : 0
Total Pages Failing   (Seg)  : 0
Total Pages Empty            : 2892
Total Pages Marked Corrupt   : 0
Total Pages Influx           : 0
Highest block SCN            : 1454468581 (2751.1454468581)

结论无坏块

方法二：bbed

[oracle@DB1 lib]$ bbed
Password: 

BBED: Release 2.0.0.0.0 - Limited Production on Fri Sep 16 10:01:26 2011

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

************* !!! For Oracle Internal Use only !!! ***************

BBED> set filename '/opt/oracle/oradata/ora9i/TS_INDX_Base.005.dbf'
        FILENAME        /opt/oracle/oradata/ora9i/TS_INDX_Base.005.dbf

BBED> set block 1444767
        BLOCK#          1444767

BBED> VERIFY 
DBVERIFY - Verification starting
FILE = /opt/oracle/oradata/ora9i/TS_INDX_Base.005.dbf
BLOCK = 1444767


DBVERIFY - Verification complete

Total Blocks Examined         : 1
Total Blocks Processed (Data) : 0
Total Blocks Failing   (Data) : 0
Total Blocks Processed (Index): 1
Total Blocks Failing   (Index): 0
Total Blocks Empty            : 0
Total Blocks Marked Corrupt   : 0
Total Blocks Influx           : 0

再次证明无坏块

方法三：rman
RMAN> backup validate datafile 19;
结果查询V$BACKUP_CORRUPTION也无坏块

方法四：使用index查询
结果也正常，没报错，alert中无错误记录

发现alert报错，但是实际没有错误，查询相关资料发现
从日志中可以看到，提示Corrupt的block对应的dba为0x04d60b9f (file 19, block 1444767)，data block的类型为6（6为trans data，所有的data和index blocks都是该类型）。Oracle发现block有可能corrupt后，进行了reread，结果为found valid data，说明数据块未损坏。Fractured block found，表示rman发现这个数据块正在被使用，这时rman会进行重新读取，如果再次失败，才认为是坏块。如果第二次尝试读取时成功，则表示数据完好，不会产生影响。此类信息在IO负载较高的情况下进行rman备份时比较容易出现。
查询系统发现，正好该时间段是系统io负载最高的时候

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ORA-00600 [ktbdchk1: bad dscn] 解决

发表于 2011 年 9 月 15 日 由 惜分飞 
启动数据库报错
SQL> startup
ORACLE instance started.

Total System Global Area  167772160 bytes
Fixed Size                  1260720 bytes
Variable Size             150995792 bytes
Database Buffers            8388608 bytes
Redo Buffers                7127040 bytes
Database mounted.
ORA-01092: ORACLE instance terminated. Disconnection forced

alert.log导错
Wed Aug 10 12:31:11 2011
Errors in file /u01/admin/xienfei/udump/xff_ora_8568.trc:
ORA-00600: internal error code, arguments: [ktbdchk1: bad dscn], [], [], [], [], [], [], []

xff_ora_8568.trc内容
[ktbdchk] -- readers_dsz -- bad dscn
scn: 0x0000.b1e60c00scn: 0x0000.0011fca1
*** 2011-08-10 12:31:11.998
ksedmp: internal or fatal error
ORA-00600: internal error code, arguments: [ktbdchk1: bad dscn], [], [], [], [], [], [], []
Current SQL statement for this session:
select ctime, mtime, stime from obj$ where obj# = :1
根据上面错误判断，错误的scn为b1e60c00，不是整个数据文件的scn错误
而应该是一个对象的scn错误，所以继续在xff_ora_8568.trc文件中查找b1e60c00
找到结果如下：
Block header dump:  0x0040007a
 Object id on Block? Y
 seg/obj: 0x12  csc: 0x00.b1e60c00  itc: 1  flg: -  typ: 1 - DATA
     fsl: 0  fnx: 0x0 ver: 0x01

 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   0x0008.02a.000001d9  0x00802341.01bb.04  ----    1  fsc 0x0000.0011ae7c

data_block_dump,data header at 0x20fd6044
===============
tsiz: 0x1fb8
hsiz: 0xea
pbl: 0x20fd6044
bdba: 0x0040007a
     76543210
flag=--------
ntab=1
nrow=108
frre=-1
fsbo=0xea
fseo=0x453
avsp=0x369
tosp=0x369
0xe:pti[0]      nrow=108        offs=0

根据这个提示，发现dba为：0040007a的对象异常，查找对应的file_id，block
SQL> SELECT DBMS_UTILITY.data_block_address_file (TO_NUMBER ('40007a', 'XXXXXXXX')) file_id,
  2          DBMS_UTILITY.data_block_address_block (TO_NUMBER ('40007a', 'XXXXXXXX')) block_id
  3    FROM DUAL;

   FILE_ID   BLOCK_ID
---------- ----------
         1        122

使用bbed查看file=1，block=122的scn情况
BBED> p ktbbh
struct ktbbh, 48 bytes                      @20      
   ub1 ktbbhtyp                             @20       0x01 (KDDBTDATA)
   union ktbbhsid, 4 bytes                  @24      
      ub4 ktbbhsg1                          @24       0x00000012
      ub4 ktbbhod1                          @24       0x00000012
   struct ktbbhcsc, 8 bytes                 @28      
      ub4 kscnbas                           @28       0xb1e60c00
      ub2 kscnwrp                           @32       0x0000
   b2 ktbbhict                              @36       1
   ub1 ktbbhflg                             @38       0x02 (NONE)
   ub1 ktbbhfsl                             @39       0x00
   ub4 ktbbhfnx                             @40       0x00000000
   struct ktbbhitl[0], 24 bytes             @44      
      struct ktbitxid, 8 bytes              @44      
         ub2 kxidusn                        @44       0x0008
         ub2 kxidslt                        @46       0x002a
         ub4 kxidsqn                        @48       0x000001d9
      struct ktbituba, 8 bytes              @52      
         ub4 kubadba                        @52       0x00802341
         ub2 kubaseq                        @56       0x01bb
         ub1 kubarec                        @58       0x04
      ub2 ktbitflg                          @60       0x0001 (NONE)
      union _ktbitun, 2 bytes               @62      
         b2 _ktbitfsc                       @62       0
         ub2 _ktbitwrp                      @62       0x0000
      ub4 ktbitbas                          @64       0x0011ae7c

果然发现scn为0xb1e60c00，现在把其修改为：0x00124ac6（注意规则，一般linux下都是倒序）
BBED> set offset 28
        OFFSET          28

BBED> m /x c64a1200
BBED-00209: invalid number (c64a1200)
小技巧，一次性修改报错，尝试一次修改一点

BBED> m /x c64a
 File: /u01/oradata/xienfei/system01.dbf (0)
 Block: 122              Offsets:   28 to   43           Dba:0x00000000
------------------------------------------------------------------------
 c64ae6b1 00000000 01000200 00000000 

 <32 bytes per line>

BBED> set offset +2
        OFFSET          30

BBED> m /x 1200
 File: /u01/oradata/xienfei/system01.dbf (0)
 Block: 122              Offsets:   30 to   45           Dba:0x00000000
------------------------------------------------------------------------
 12000000 00000100 02000000 00000800 

 <32 bytes per line>

BBED> set offset -2
        OFFSET          28

BBED> dump
 File: /u01/oradata/xienfei/system01.dbf (0)
 Block: 122              Offsets:   28 to   43           Dba:0x00000000
------------------------------------------------------------------------
 c64a1200 00000000 01000200 00000000 

 <32 bytes per line>

BBED> sum apply
Check value for File 0, Block 122:
current = 0x3a4e, required = 0x3a4e

SQL> startup
ORACLE instance started.

Total System Global Area  167772160 bytes
Fixed Size                  1260720 bytes
Variable Size             150995792 bytes
Database Buffers            8388608 bytes
Redo Buffers                7127040 bytes
Database mounted.
Database opened.
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