[20181122]模拟ORA-08103错误.txt

[20181122]模拟ORA-08103错误.txt

$ oerr ora 8103
08103, 00000, "object no longer exists"
// *Cause:  The object has been deleted by another user since the operation
//          began, or a prior incomplete recovery restored the database to
//          a point in time during the deletion of the object.
// *Action: Delete the object if this is the result of an incomplete
//          recovery.

在 Master Note for Handling Oracle Database Corruption Issues (文档 ID 1088018.1)中对ORA-8103错误的描述如下：

The object has been deleted by another user since the operation began.
If the error is reproducible, following may be the reasons:-
a.) The header block has an invalid block type.
b.) The data_object_id (seg/obj) stored in the block is different than the data_object_id stored in the segment header.

See dba_objects.data_object_id and compare it to the decimal value stored in the block (field seg/obj).

--//以前做过的测试.链接:http://blog.itpub.net/267265/viewspace-2131848/
--//听别人提起高水位下的块出现了未格式化的块.自己模拟测试看看.

1.环境:
SCOTT@book> @ ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

--//建立表空间:
CREATE TABLESPACE TEA DATAFILE
  '/mnt/ramdisk/book/tea01.dbf' SIZE 40M AUTOEXTEND ON NEXT 1M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT MANUAL
FLASHBACK ON;

--//顺便做1个备份.
RMAN> backup as copy datafile 6 format '/home/oracle/backup/%b' ;
Starting backup at 2018-11-22 16:22:12
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=67 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=94 device type=DISK
allocated channel: ORA_DISK_3
channel ORA_DISK_3: SID=106 device type=DISK
channel ORA_DISK_1: starting datafile copy
input datafile file number=00006 name=/mnt/ramdisk/book/tea01.dbf
output file name=/home/oracle/backup/tea01.dbf tag=TAG20181122T162213 RECID=13 STAMP=992881334
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01
Finished backup at 2018-11-22 16:22:15

Starting Control File and SPFILE Autobackup at 2018-11-22 16:22:15
piece handle=/u01/app/oracle/fast_recovery_area/BOOK/autobackup/2018_11_22/o1_mf_s_992881335_fzdssq4g_.bkp comment=NONE
Finished Control File and SPFILE Autobackup at 2018-11-22 16:22:16

2.建立测试环境:
SCOTT@book> create table t tablespace tea as select * from all_objects where rownum<=1e4;
Table created.

SCOTT@book> select object_id,data_object_id from dba_objects where object_name = 'T' and owner = user;
 OBJECT_ID DATA_OBJECT_ID
---------- --------------
     90463          90463

SCOTT@book> select segment_type, HEADER_FILE, HEADER_BLOCK from dba_segments where owner = user and segment_name = 'T';
SEGMENT_TYPE       HEADER_FILE HEADER_BLOCK
------------------ ----------- ------------
TABLE                        6          128

SCOTT@book> select FILE_ID, block_id, blocks from dba_extents where owner = user and segment_name = 'T';
   FILE_ID   BLOCK_ID     BLOCKS
---------- ---------- ----------
         6        128          8
         6        136          8
         6        144          8
         6        152          8
         6        160          8
         6        168          8
         6        176          8
         6        184          8
         6        192          8
         6        200          8
         6        208          8
         6        216          8
         6        224          8
         6        232          8
         6        240          8
         6        248          8
         6        256        128
17 rows selected.

2.破坏数据块看看:
SCOTT@book> alter system flush buffer_cache;
System altered.

SCOTT@book> select max(rowid) from t ;
MAX(ROWID)
------------------
AAAWFfAAGAAAAEBABJ

SCOTT@book> @ rowid AAAWFfAAGAAAAEBABJ
    OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA                  TEXT
---------- ---------- ---------- ---------- -------------------- -------------------- ----------------------------------------
     90463          6        257         73  0x1800101           6,257                alter system dump datafile 6 block 257 ;

--//dba=6,257块上有数据.

SCOTT@book> insert into t  select * from all_objects where rownum<=1;
1 row created.

SCOTT@book> commit ;
Commit complete.

SCOTT@book> alter system flush buffer_cache;
System altered.

SCOTT@book> @ rowid AAAWFfAAGAAAAECAAA
    OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA                  TEXT
---------- ---------- ---------- ---------- -------------------- -------------------- ----------------------------------------
     90463          6        258          0  0x1800102           6,258                alter system dump datafile 6 block 258 ;

--//dba=6,258块上有数据.通过bbed观察dba=6,259
BBED> map dba 6,259
 File: /mnt/ramdisk/book/tea01.dbf (6)
 Block: 259                                   Dba:0x01800103
------------------------------------------------------------
 KTB Data Block (Table/Cluster)
 struct kcbh, 20 bytes                      @0
 struct ktbbh, 72 bytes                     @20
 struct kdbh, 14 bytes                      @92
 struct kdbt[0], 0 bytes                    @106
 sb2 kdbr[0]                                @106
 ub1 freespace[8082]                        @106
 ub1 rowdata[0]                             @8188
 ub4 tailchk                                @8188

--//可以发现dba=6,259已经格式化.但是没有数据.
SCOTT@book> select count(*) from t;
  COUNT(*)
----------
     10001
--//OK一切正常.现在破坏dba=6,259

BBED> set offset 0
        OFFSET          0
--//注意一定要设置offset 0,不然可能copy仅仅剩下的部分.

BBED> copy filename '/home/oracle/backup/tea01.dbf' block 259 to filename '/mnt/ramdisk/book/tea01.dbf' block 259
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
 File: /mnt/ramdisk/book/tea01.dbf (6)
 Block: 259                                                  Offsets:    0 to   63                                               Dba:0x01800103
------------------------------------------------------------------------------------------------------------------------------------------------
 00a20000 03018001 00000000 00000105 83a70000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
<64 bytes per line>

--//现在已经未格式化块.

4.继续测试:
SCOTT@book> alter system flush buffer_cache;
System altered.

SCOTT@book> select count(*) from t;
select count(*) from t
*
ERROR at line 1:
ORA-08103: object no longer exists
--//再线ora-08103.
--//而执行如下不会报错:
SCOTT@book> select count(*) from t where rownum<=10001;
  COUNT(*)
----------
     10001
SCOTT@book> select count(*) from t where rownum<=10002;
select count(*) from t where rownum<=10002
                     *
ERROR at line 1:
ORA-08103: object no longer exists
    
--//检查跟踪文件:
kcbzibmlt: dump suspect buffer, err=8103
buffer tsn: 7 rdba: 0x01800103 (6/259)
scn: 0x0000.00000000 seq: 0x01 flg: 0x05 tail: 0x00000001
frmt: 0x02 chkval: 0xa783 type: 0x00=unknown
Hex dump of corrupt header 4 = CORRUPT
Dump of memory from 0x000000006A4EA000 to 0x000000006A4EA014
06A4EA000 0000A200 01800103 00000000 05010000  [................]
06A4EA010 0000A783                             [....]
Hex dump of block: st=4, typ_found=0
Dump of memory from 0x000000006A4EA000 to 0x000000006A4EC000
06A4EA000 0000A200 01800103 00000000 05010000  [................]
06A4EA010 0000A783 00000000 00000000 00000000  [................]
06A4EA020 00000000 00000000 00000000 00000000  [................]
        Repeat 508 times
06A4EBFF0 00000000 00000000 00000000 00000001  [................]
Dump of buffer cache at level 8 for tsn=7 rdba=25166080

--//可以发现dba =6,259报错.

5.如何跳过呢?
--//我测试仅仅设置坏块.如果真有数据可以通过一些特殊的方式读出来,这个给看运气.通过10231事件跳过坏块

$ oerr ora 10231
10231, 00000, "skip corrupted blocks on _table_scans_"
// *Cause:
// *Action: such blocks are skipped in table scans, and listed in trace files
--//alter session set db_file_multiblock_read_count=1 ;
ALTER SESSION SET EVENTS '10231 TRACE NAME CONTEXT FOREVER, LEVEL 10';

SCOTT@book> ALTER SESSION SET EVENTS '10231 TRACE NAME CONTEXT FOREVER, LEVEL 10';
Session altered.

SCOTT@book> select count(*) from t ;
select count(*) from t
*
ERROR at line 1:
ORA-08103: object no longer exists

--//不行.在bbed设置坏块看看.
BBED> set dba 6,259
        DBA             0x01800103 (25166083 6,259)

BBED> corrupt
Block marked media corrupt.

BBED> sum apply ;
Check value for File 6, Block 259:
current = 0xa683, required = 0xa683

SCOTT@book> select count(*) from t ;
  COUNT(*)
----------
     10001

--//ok.跳过坏块.