在11G中ORACLE提供DBMS_DDL_INTERNAL.SWAP_BOOTSTRAP直接切换boostrap表到用户指定的表，但是前提数据库必须启动到upgrade状态，如果bootstrap块损坏，数据库都不能启动，当然也不能使用DBMS_DDL_INTERNAL.SWAP_BOOTSTRAP。DBMS_DDL_INTERNAL.SWAP_BOOTSTRAP这个工具还是有很多作用的，将在后面会测试。
下面是测试直接使用dd清除bootstrap$表的块，再使用dd其它数据库的块来恢复bootstrap$ge 。注意下面测试平台，请非在生产环境测试。
1 环境介绍
是在linux平台，ORACLE 11.2.0.3环境下，其它的环境没有做测试
www.cdhtz.com > select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production PL/SQL Release 11.2.0.3.0 - Production CORE 11.2.0.3.0 Production TNS for Linux: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production www.cdhtz.com > !uname -a Linux orcl9i 2.6.9-89.EL #1 Mon Apr 20 10:22:29 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux
2 BOOTSTRAP$表
www.cdhtz.com > select open_mode from v$database;
OPEN_MODE
--------------------
READ WRITE
www.cdhtz.com > select name from v$dbfile;
NAME
--------------------------------------------------------------------------------
/oracle/app/oracle/oradata/orcl1123/system01.dbf
/oracle/app/oracle/oradata/orcl1123/sysaux01.dbf
/oracle/app/oracle/oradata/orcl1123/undo1.dbf
/oracle/app/oracle/oradata/orcl1123/user02.dbf
/oracle/app/oracle/oradata/orcl1123/user01.dbf
这里可以看到BOOTSTRAP$表使用的块是520到527
www.cdhtz.com > @extent.sql
Enter value for owner: sys
Enter value for segment_name: bootstrap$
Enter value for tablespace_name:
FILE BLOCK
OWNER:SEGMENT_NAME ID FNO EXTENT_ID BEGIN_END
------------------------ ----- ----- ---------- -------------------------
SYS.BOOTSTRAP$ 1 1 0 520~527
******************************
Total:
www.cdhtz.com > shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
3 dd数据文件
这里dd数据的时候，千万要记住在conv=notrunc增加上，不然后果就悲剧了 www.cdhtz.com > !dd if=/dev/zero of=/oracle/app/oracle/oradata/orcl1123/system01.dbf bs=8192 seek=520 count=8 conv=notrunc 8+0 records in 8+0 records out
4 数据库报坏块
www.cdhtz.com > startup
ORACLE instance started.
Total System Global Area 2137886720 bytes
Fixed Size 2230072 bytes
Variable Size 1493174472 bytes
Database Buffers 637534208 bytes
Redo Buffers 4947968 bytes
Database mounted.
ORA-01092: ORACLE instance terminated. Disconnection forced
ORA-00704: bootstrap process failure
ORA-01578: ORACLE data block corrupted (file # 1, block # 520)
ORA-01110: data file 1: '/oracle/app/oracle/oradata/orcl1123/system01.dbf'
Process ID: 14852
Session ID: 1 Serial number: 5
这里可以看到数据库启动的时候报520是坏块的错误
下面来看看10046生成的TRACE文件信息
www.cdhtz.com > oradebug setmypid
Statement processed.
www.cdhtz.com > oradebug event 10046 trace name context forever,level 12;
Statement processed.
www.cdhtz.com > oradebug tracefile_name;
/oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_15095.trc
WAIT #182936778792: nam='instance state change' ela= 874 layer=2 value=1 waited=1 obj#=-1 tim=1416486056350145
WAIT #182936778792: nam='db file sequential read' ela= 9 file#=1 block#=520 blocks=1 obj#=-1 tim=1416486056350361
Hex dump of (file 1, block 520)
这里可以看到dump 520这个块的内容，从这里可以看到块完全是一个空块
Dump of memory from 0x00000000B2F66000 to 0x00000000B2F68000
0B2F66000 0000A200 00400208 00000000 01010000 [......@.........]
0B2F66010 00000000 00000000 00000000 00000000 [................]
Repeat 509 times
0B2F67FF0 00000000 00000000 00000000 00000001 [................]
Corrupt block relative dba: 0x00400208 (file 1, block 520)
Completely zero block found during buffer read
Reading datafile '/oracle/app/oracle/oradata/orcl1123/system01.dbf' for corruption at rdba: 0x00400208 (file 1, block 520)
WAIT #182936778792: nam='Disk file Mirror Read' ela= 4 fileno=1 blkno=520 filetype=0 obj#=-1 tim=1416486056351002
Reread (file 1, block 520) found same corrupt data (no logical check)
...............
Byte offset to file# 1 block# 520 is 4259840
Incident 464209 created, dump file: /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/incident/incdir_464209/orcl1123_ora_15095_i464209.trc
ORA-01578: ORACLE data block corrupted (file # 1, block # 520)
ORA-01110: data file 1: '/oracle/app/oracle/oradata/orcl1123/system01.dbf'
ORA-00704: bootstrap process failure
ORA-01578: ORACLE data block corrupted (file # 1, block # 520)
ORA-01110: data file 1: '/oracle/app/oracle/oradata/orcl1123/system01.dbf'
ORA-00704: bootstrap process failure
ORA-01578: ORACLE data block corrupted (file # 1, block # 520)
ORA-01110: data file 1: '/oracle/app/oracle/oradata/orcl1123/system01.dbf'
*** 2014-11-20 20:20:58.149
USER (ospid: 15095): terminating the instance due to error 704
EXEC #182936778792:c=726890,e=1999361,p=1,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=0,tim=1416486058194414
ERROR #182936778792:err=1092 tim=1416486058194441
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5 DD复制其它数据库块
www.cdhtz.com > !dd if=/oracle/app/oracle/oradata/test/system01.dbf of=/oracle/app/oracle/oradata/orcl1123/system01.dbf bs=8192 count=8 seek=520 skip=520 conv=notrunc
8+0 records in
8+0 records out
这里直接使用dd复制其它数据库的块过来，因为bootstrap$在相同的版本内容都是一致的，其实基本上不会发生变化的。其实使用DD复制还可以使用system undo段的。
[oracle@www.htz.pw sql]$sqlplus / as sysdba
SQL*Plus: Release 11.2.0.3.0 Production on Thu Nov 20 20:23:16 2014
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Connected to an idle instance.
www.cdhtz.com > startup
ORACLE instance started.
Total System Global Area 2137886720 bytes
Fixed Size 2230072 bytes
Variable Size 1493174472 bytes
Database Buffers 637534208 bytes
Redo Buffers 4947968 bytes
Database mounted.
Database opened.
这里看到数据库已经正常启动
下面查看一下块的kcbh的信息
www.cdhtz.com > select instance_name,status from v$instance;
INSTANCE_NAME STATUS
---------------- ------------
orcl1123 OPEN
BBED> set block 520
BLOCK# 520
BBED> map
File: /oracle/app/oracle/oradata/orcl1123/system01.dbf (0)
Block: 520 Dba:0x00000000
------------------------------------------------------------
Unlimited Data Segment Header
struct kcbh, 20 bytes @0
struct ktech, 72 bytes @20
struct ktemh, 16 bytes @92
struct ktetb[1], 8 bytes @108
struct ktshc, 8 bytes @4148
struct ktsfs_seg[1], 20 bytes @4156
struct ktsfs_txn[16], 320 bytes @4176
ub4 tailchk @8188
BBED> p kcbh
struct kcbh, 20 bytes @0
ub1 type_kcbh @0 0x10
ub1 frmt_kcbh @1 0xa2
ub1 spare1_kcbh @2 0x00
ub1 spare2_kcbh @3 0x00
ub4 rdba_kcbh @4 0x00400208
ub4 bas_kcbh @8 0x00000252
ub2 wrp_kcbh @12 0x0000
ub1 seq_kcbh @14 0x01
ub1 flg_kcbh @15 0x04 (KCBHFCKV)
ub2 chkval_kcbh @16 0xe443
ub2 spare3_kcbh @18 0x0000
BBED> set block 519
BLOCK# 519
BBED> map
File: /oracle/app/oracle/oradata/orcl1123/system01.dbf (0)
Block: 519 Dba:0x00000000
------------------------------------------------------------
KTB Data Block (Index Leaf)
struct kcbh, 20 bytes @0
struct ktbbh, 72 bytes @20
struct kdxle, 32 bytes @92
sb2 kd_off[359] @124
ub1 freespace[234] @842
ub1 rowdata[7044] @1076
ub4 tailchk @8188
BBED> p kcbh
struct kcbh, 20 bytes @0
ub1 type_kcbh @0 0x06
ub1 frmt_kcbh @1 0xa2
ub1 spare1_kcbh @2 0x00
ub1 spare2_kcbh @3 0x00
ub4 rdba_kcbh @4 0x00400207
ub4 bas_kcbh @8 0x005cea63
ub2 wrp_kcbh @12 0x0000
ub1 seq_kcbh @14 0x01
ub1 flg_kcbh @15 0x06 (KCBHFDLC, KCBHFCKV)
ub2 chkval_kcbh @16 0x8f8a
ub2 spare3_kcbh @18 0x0000
这里发现2个块的SCN值完全不一样，怀疑ORACLE在启动的时候没有去验证BOOTSTRAP$块的SCN值的情况，后面再去测试一下
6 DBV验证数据文件
www.cdhtz.com > !dbv file=/oracle/app/oracle/oradata/orcl1123/system01.dbf DBVERIFY: Release 11.2.0.3.0 - Production on Thu Nov 20 22:32:26 2014 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /oracle/app/oracle/oradata/orcl1123/system01.dbf Page 392 is marked corrupt Corrupt block relative dba: 0x00400188 (file 1, block 392) Completely zero block found during dbv: Page 393 is marked corrupt Corrupt block relative dba: 0x00400189 (file 1, block 393) Completely zero block found during dbv: Page 394 is marked corrupt Corrupt block relative dba: 0x0040018a (file 1, block 394) Completely zero block found during dbv: Page 395 is marked corrupt Corrupt block relative dba: 0x0040018b (file 1, block 395) Completely zero block found during dbv: Page 396 is marked corrupt Corrupt block relative dba: 0x0040018c (file 1, block 396) Completely zero block found during dbv: Page 397 is marked corrupt Corrupt block relative dba: 0x0040018d (file 1, block 397) Completely zero block found during dbv: Page 398 is marked corrupt Corrupt block relative dba: 0x0040018e (file 1, block 398) Completely zero block found during dbv: Page 399 is marked corrupt Corrupt block relative dba: 0x0040018f (file 1, block 399) Completely zero block found during dbv: 这里报393与399是由于I_FILE1索引的原因，在之前DD清空I_FILE1块。 原来做的操作 www.cdhtz.com > !dd if=/dev/zero of=/oracle/app/oracle/oradata/orcl1123/system01.dbf bs=8192 seek=392 count=8 conv=notrunc 8+0 records in 8+0 records out DBVERIFY - Verification complete Total Pages Examined : 96000 Total Pages Processed (Data) : 64163 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 13644 Total Pages Failing (Index): 0 Total Pages Processed (Other): 3531 Total Pages Processed (Seg) : 1 Total Pages Failing (Seg) : 0 Total Pages Empty : 14654 Total Pages Marked Corrupt : 8 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 1080566554 (0.1080566554)
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recover bootstrap$ corrupt block with dd tool：等您坐沙发呢！