Oracle數據塊的損壞可以分爲物理損壞和邏輯損壞,參照
http://blog.csdn.net/yidian815/article/details/39990803
物理損壞和邏輯損壞發生的場景不同,因此處理的方式方法也就不同。在很多情況下,相同的損壞塊處理方法對於物理損壞和邏輯損壞會產生不同的結果。對於物理損壞的模擬是比較容易的,而對邏輯損壞的模擬卻不常見。
物理損壞:
要模擬物理損壞,我們只需直接手工編輯物理塊既可(通過UTRAEDIT\BBED等),如
SQL> select object_name,dbms_rowid.rowid_block_number(rowid) from t1 where rownum < 9;
OBJECT_NAME DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)
------------------------------ ------------------------------------
ICOL$ 20
I_USER1 20
CON$ 20
UNDO$ 20
C_COBJ# 20
I_OBJ# 20
PROXY_ROLE_DATA$ 20
I_IND1 20
8 rows selected.
BBED> set file 5
FILE# 5
BBED> set block 20
BLOCK# 20
BBED> finr /c PROXY
BBED-00200: invalid keyword (finr)
BBED> find /c PROXY
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Offsets: 4223 to 4734 Dba:0x01400014
------------------------------------------------------------------------
50524f58 595f524f 4c455f44 41544124 5f32ff02 c11c02c1 1c05494e 44455807
786e0414 09191d07 786e0414 09191d13 32303130 2d30342d 32303a30 383a3234
3a323805 56414c49 44014e01 4e014e2c 000c0749 5f555345 5223ff02 c10c02c1
0c05494e 44455807 786e0414 09191d07 786e0414 09191d13 32303130 2d30342d
32303a30 383a3234 3a323805 56414c49 44014e01 4e014e2c 000c0649 5f434f4c
31ff02c1 2e02c12e 05494e44 45580778 6e041409 191d0778 6e041409 191d1332
3031302d 30342d32 303a3038 3a32343a 32380556 414c4944 014e014e 014e2c00
0c07495f 43434f4c 32ff02c1 3802c138 05494e44 45580778 6e041409 191d0778
6e041409 191d1332 3031302d 30342d32 303a3038 3a32343a 32380556 414c4944
014e014e 014e2c00 0c07495f 43444546 33ff02c1 3502c135 05494e44 45580778
6e041409 191d0778 6e041409 191d1332 3031302d 30342d32 303a3038 3a32343a
32380556 414c4944 014e014e 014e2c00 0c07495f 49434f4c 31ff02c1 2902c129
05494e44 45580778 6e041409 191d0778 6e041409 191d1332 3031302d 30342d32
303a3038 3a32343a 32380556 414c4944 014e014e 014e2c00 0c07495f 43444546
31ff02c1 3302c133 05494e44 45580778 6e041409 191d0778 6e041409 191d1332
3031302d 30342d32 303a3038 3a32343a 32380556 414c4944 014e014e 014e2c00
<32 bytes per line>
BBED> dump /v
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Offsets: 4223 to 4734 Dba:0x01400014
-------------------------------------------------------
50524f58 595f524f 4c455f44 41544124 l PROXY_ROLE_DATA$
5f32ff02 c11c02c1 1c05494e 44455807 l _2........INDEX.
786e0414 09191d07 786e0414 09191d13 l xn......xn......
32303130 2d30342d 32303a30 383a3234 l 2010-04-20:08:24
3a323805 56414c49 44014e01 4e014e2c l :28.VALID.N.N.N,
000c0749 5f555345 5223ff02 c10c02c1 l ...I_USER#......
0c05494e 44455807 786e0414 09191d07 l ..INDEX.xn......
786e0414 09191d13 32303130 2d30342d l xn......2010-04-
32303a30 383a3234 3a323805 56414c49 l 20:08:24:28.VALI
44014e01 4e014e2c 000c0649 5f434f4c l D.N.N.N,...I_COL
31ff02c1 2e02c12e 05494e44 45580778 l 1........INDEX.x
6e041409 191d0778 6e041409 191d1332 l n......xn......2
3031302d 30342d32 303a3038 3a32343a l 010-04-20:08:24:
32380556 414c4944 014e014e 014e2c00 l 28.VALID.N.N.N,.
0c07495f 43434f4c 32ff02c1 3802c138 l ..I_CCOL2...8..8
05494e44 45580778 6e041409 191d0778 l .INDEX.xn......x
6e041409 191d1332 3031302d 30342d32 l n......2010-04-2
303a3038 3a32343a 32380556 414c4944 l 0:08:24:28.VALID
014e014e 014e2c00 0c07495f 43444546 l .N.N.N,...I_CDEF
33ff02c1 3502c135 05494e44 45580778 l 3...5..5.INDEX.x
6e041409 191d0778 6e041409 191d1332 l n......xn......2
3031302d 30342d32 303a3038 3a32343a l 010-04-20:08:24:
32380556 414c4944 014e014e 014e2c00 l 28.VALID.N.N.N,.
0c07495f 49434f4c 31ff02c1 2902c129 l ..I_ICOL1...)..)
05494e44 45580778 6e041409 191d0778 l .INDEX.xn......x
6e041409 191d1332 3031302d 30342d32 l n......2010-04-2
303a3038 3a32343a 32380556 414c4944 l 0:08:24:28.VALID
014e014e 014e2c00 0c07495f 43444546 l .N.N.N,...I_CDEF
31ff02c1 3302c133 05494e44 45580778 l 1...3..3.INDEX.x
6e041409 191d0778 6e041409 191d1332 l n......xn......2
3031302d 30342d32 303a3038 3a32343a l 010-04-20:08:24:
32380556 414c4944 014e014e 014e2c00 l 28.VALID.N.N.N,.
<16 bytes per line>
BBED> modify /c abcde
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Offsets: 4223 to 4734 Dba:0x01400014
------------------------------------------------------------------------
61626364 655f524f 4c455f44 41544124 5f32ff02 c11c02c1 1c05494e 44455807
786e0414 09191d07 786e0414 09191d13 32303130 2d30342d 32303a30 383a3234
3a323805 56414c49 44014e01 4e014e2c 000c0749 5f555345 5223ff02 c10c02c1
0c05494e 44455807 786e0414 09191d07 786e0414 09191d13 32303130 2d30342d
32303a30 383a3234 3a323805 56414c49 44014e01 4e014e2c 000c0649 5f434f4c
31ff02c1 2e02c12e 05494e44 45580778 6e041409 191d0778 6e041409 191d1332
3031302d 30342d32 303a3038 3a32343a 32380556 414c4944 014e014e 014e2c00
0c07495f 43434f4c 32ff02c1 3802c138 05494e44 45580778 6e041409 191d0778
6e041409 191d1332 3031302d 30342d32 303a3038 3a32343a 32380556 414c4944
014e014e 014e2c00 0c07495f 43444546 33ff02c1 3502c135 05494e44 45580778
6e041409 191d0778 6e041409 191d1332 3031302d 30342d32 303a3038 3a32343a
32380556 414c4944 014e014e 014e2c00 0c07495f 49434f4c 31ff02c1 2902c129
05494e44 45580778 6e041409 191d0778 6e041409 191d1332 3031302d 30342d32
303a3038 3a32343a 32380556 414c4944 014e014e 014e2c00 0c07495f 43444546
31ff02c1 3302c133 05494e44 45580778 6e041409 191d0778 6e041409 191d1332
3031302d 30342d32 303a3038 3a32343a 32380556 414c4944 014e014e 014e2c00
<32 bytes per line>
SQL> alter system flush buffer_cache;
System altered.
SQL> select object_name,dbms_rowid.rowid_block_number(rowid) from t1 where rownum < 9;
select object_name,dbms_rowid.rowid_block_number(rowid) from t1 where rownum < 9
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 5, block # 20)
ORA-01110: data file 5: '/home/app/oraten/oradata/oraten/tbs101.dbf'
而對物理損壞的修復也非常簡單( 上面修改的並不是第7條記錄):
BBED> sum apply
Check value for File 5, Block 20:
current = 0xb5e0, required = 0xb5e0
SQL> alter system flush buffer_cache;
System altered.
SQL> select object_name,dbms_rowid.rowid_block_number(rowid) from t1 where object_name like '%abcde%';
OBJECT_NAME DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)
------------------------------ ------------------------------------
I_abcde_ROLE_DATA$_2 20
對於邏輯損壞的模擬,確實比較麻煩,因爲只有oracle才知道數據塊的內部邏輯結構。今天我們嘗試模擬一種邏輯錯誤。我們指定oracle的數據是以row爲單位存儲在數據塊中的,而每個row的第一個byte具有特殊含義,該字節的每一個位都表示不同的含義,如下圖
如果我們通過bbed手工修改該byte的存儲內容,那麼oracle就有可能不能很好的識別該條記錄,從而引發邏輯錯誤。
BBED> set file 5
FILE# 5
BBED> set block 20
BLOCK# 20
BBED> map /v
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Dba:0x01400014
------------------------------------------------------------
KTB Data Block (Table/Cluster)
struct kcbh, 20 bytes @0
ub1 type_kcbh @0
ub1 frmt_kcbh @1
ub1 spare1_kcbh @2
ub1 spare2_kcbh @3
ub4 rdba_kcbh @4
ub4 bas_kcbh @8
ub2 wrp_kcbh @12
ub1 seq_kcbh @14
ub1 flg_kcbh @15
ub2 chkval_kcbh @16
ub2 spare3_kcbh @18
struct ktbbh, 96 bytes @20
ub1 ktbbhtyp @20
union ktbbhsid, 4 bytes @24
struct ktbbhcsc, 8 bytes @28
b2 ktbbhict @36
ub1 ktbbhflg @38
ub1 ktbbhfsl @39
ub4 ktbbhfnx @40
struct ktbbhitl[3], 72 bytes @44
struct kdbh, 14 bytes @124
ub1 kdbhflag @124
b1 kdbhntab @125
b2 kdbhnrow @126
sb2 kdbhfrre @128
sb2 kdbhfsbo @130
sb2 kdbhfseo @132
b2 kdbhavsp @134
b2 kdbhtosp @136
struct kdbt[1], 4 bytes @138
b2 kdbtoffs @138
b2 kdbtnrow @140
sb2 kdbr[96] @142
ub1 freespace[868] @334
ub1 rowdata[6986] @1202
ub4 tailchk @8188
BBED> p *kdbr[1]
rowdata[6844]
-------------
ub1 rowdata[6844] @8046 0x2c
BBED> set offset 8046
OFFSET 8046
BBED> x /rccnncttccccc
rowdata[6844] @8046
-------------
flag@8046: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8047: 0x00
cols@8048: 12
col 0[7] @8049: I_USER1
col 1[0] @8057: *NULL*
col 2[2] @8058: 44
col 3[2] @8061: 44
col 4[5] @8064: INDEX
col 5[7] @8070: 2010-04-20 08:24:28
col 6[7] @8078: 2010-04-20 08:24:28
col 7[19] @8086: 2010-04-20:08:24:28
col 8[5] @8106: VALID
col 9[1] @8112: N
col 10[1] @8114: N
col 11[1] @8116: N
BBED> set offset 8046
OFFSET 8046
BBED> modify /x ff
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Offsets: 8046 to 8191 Dba:0x01400014
------------------------------------------------------------------------
ff000c07 495f5553 455231ff 02c12d02 c12d0549 4e444558 07786e04 1409191d
07786e04 1409191d 13323031 302d3034 2d32303a 30383a32 343a3238 0556414c
4944014e 014e014e 2c000c05 49434f4c 24ff02c1 1502c103 05544142 4c450778
6e041409 191d0778 6e041409 211a1332 3031302d 30342d32 303a3038 3a32343a
32380556 414c4944 014e014e 014e0106 5af8
<32 bytes per line>
BBED> x /rccnncttccccc
rowdata[6844] @8046
-------------
flag@8046: 0xff (KDRHFN, KDRHFP, KDRHFL, KDRHFF, KDRHFD, KDRHFH, KDRHFC, KDRHFK)
lock@8047: 0x00
cols@8048: 0
ckix@8049: 7
BBED> sum apply
Check value for File 5, Block 20:
current = 0xb533, required = 0xb533
此時我們通過sqlpus查詢並編輯t1
SQL> alter system flush buffer_cache;
System altered.
SQL> select count(*) from t1;
COUNT(*)
----------
22944
SQL> select sum(length(object_name)) from t1;
SUM(LENGTH(OBJECT_NAME))
------------------------
531915
SQL> update t1 set object_name = rownum;
update t1 set object_name = rownum
*
ERROR at line 1:
ORA-00607: Internal error occurred while making a change to a data block
ORA-00600: internal error code, arguments: [kddummy_blkchk], [5], [20], [6251],
[], [], [], []
SQL> rollback;
Rollback complete.
SQL> update t1 set object_name = rownum;
update t1 set object_name = rownum
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 5, block # 20)
ORA-01110: data file 5: '/home/app/oraten/oradata/oraten/tbs101.dbf'
可見此時oracle認爲發生了邏輯錯誤,查看block20的標誌位發現, 邏輯損壞的標記(14字節修改位ff,tailchk中包含ff)已經打上。
BBED> set file 5
FILE# 5
BBED> set block 20
BLOCK# 20
BBED> set offset 14
OFFSET 14
BBED> dump /v count 12
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Offsets: 14 to 25 Dba:0x01400014
-------------------------------------------------------
ff0438b5 00000100 00001ecb l ..8.........
<16 bytes per line>
BBED> set offset 8188
OFFSET 8188
BBED> dump /v
File: /home/app/oraten/oradata/oraten/tbs101.dbf (5)
Block: 20 Offsets: 8188 to 8191 Dba:0x01400014
-------------------------------------------------------
ff060000 l ....
<16 bytes per line>
而邏輯損壞的修復,通常是使用dbms_repair 包將損壞塊忽略
SQL> exec dbms_repair.skip_corrupt_blocks('SYS','T1');
PL/SQL procedure successfully completed.
SQL> update t1 set object_name=rownum;
22849 rows updated.
SQL> commit;
Commit complete.