有人在Google新闻组上提出了一个问题:How can I get the BBED password?继而引发了一场很有意思的讨论
后来Pete Finnigan也在他的Blog写了一篇文章An interesting thread on Oraclel about BBED描述这次有意思的探讨
在讨论中有一个有趣的观点提到如果这个工具被广泛传播那么可能有些人不是用BBED来修复数据意外的破坏可能更为多见最终的后果可能是Oracle彻底把这个工具移除
BBED是Block Browser/Editor的缩写是Oracle的一个内部工具不对外发布文档及支持
BBED随软件发布但是我们需要进行简单的relink才能使用relink请参考:How to compile Oracleg BBED tools
虽然BBED工具的使用存在很多风险但是如果利用得当可以以之解决很多棘手的问题
本文简单介绍一下如何用BBED模拟坏块以练习坏块修复等技术此前我曾经介绍过另外一种方法请参考:Oracle中模拟及修复数据块损坏
创建测试表
[oracle@jumper conner]$ sqlplus / as sysdba
SQL*Plus: Release Production on Sun Sep ::
Copyright (c) Oracle Corporation All rights reserved
Connected to:
Oraclei Enterprise Edition Release Production
With the Partitioning option
JServer Release Production
SQL> create table bbed tablespace users as select * from dba_tables;
Table created
SQL> select count(*) from bbed;
COUNT(*)
SQL> col segment_name for a
SQL> select segment_namefile_idblock_id from dba_extents where segment_name=BBED;
SEGMENT_NA FILE_ID BLOCK_ID
BBED
BBED
BBED
SQL> select count(*) from bbed;
COUNT(*)
创建BBED参数文件等
[oracle@jumper conner]$ more filelisttxt
/opt/oracle/oradata/conner/systemdbf
/opt/oracle/oradata/conner/undotbsdbf
/opt/oracle/oradata/conner/usersdbf
[oracle@jumper conner]$ more parbbd
blocksize=
listfile=filelisttxt
mode=edit
使用BBED
[oracle@jumper conner]$ bbed parfile=parbbd
Password:
BBED: Release Limited Production on Sun Sep ::
Copyright (c) Oracle Corporation All rights reserved
************* !!! For Oracle Internal Use only !!! ***************
BBED> set file
FILE#
BBED> show
FILE#
BLOCK#
OFFSET
DBA xc ( )
FILENAME /opt/oracle/oradata/conner/usersdbf
BIFILE bifilebbd
LISTFILE filelisttxt
BLOCKSIZE
MODE Edit
EDIT Unrecoverable
IBASE Dec
OBASE Dec
WIDTH
COUNT
LOGFILE logbbd
SPOOL No
回滚误操作
如果操作中发生误操作可以使用revert命令回滚
BBED> modify /x xc
File: /opt/oracle/oradata/conner/usersdbf ()
Block: Offsets: to Dba:xc
c
< bytes per line>
BBED> revert
All changes made in this session will be rolled back Proceed? (Y/N) Y
Reverted file /opt/oracle/oradata/conner/usersdbf block
Warning: contents of previous BIFILE will be lost Proceed? (Y/N) Y
改写数据块
模拟坏块
BBED> modify file block
File: /opt/oracle/oradata/conner/usersdbf ()
Block: Offsets: to Dba:xc
e
cf cf fe fc
ff cde d ffffc bc c c
c ffc c eff c c e ffffffff
ffffffff a a e
e c ffffe fffe ee f c
c e fef ff c e fff
c c cf c f f
fe c dff ffcb c cc c
ff c c eff cc eff ffffffff
ffffffa a e
e cff ffef ffe eef c
c ef efff c ef ff c
cc f c c f f
< bytes per line>
检查数据块损坏
使用verify命令可以发现刚才修改的file block 已经被标记为损坏
BBED> verify
DBVERIFY Verification starting
FILE = /opt/oracle/oradata/conner/usersdbf
BLOCK =
Block is corrupt
***
Corrupt block relative dba: xc (file block )
Bad check value found during verification
Data in bad block
type: format: rdba: xc
last change scn: xab seq: x flg: x
consistency value in tail: xb
check value in block header: x computed block checksum: xe
spare: x spare: x spare: x
***
DBVERIFY Verification complete
Total Blocks Examined :
Total Blocks Processed (Data) :
Total Blocks Failing (Data) :
Total Blocks Processed (Index):
Total Blocks Failing (Index):
Total Blocks Empty :
Total Blocks Marked Corrupt :
Total Blocks Influx :
BBED> quit
使用DBV检查
[oracle@jumper conner]$ dbv file=usersdbf blocksize=
DBVERIFY: Release Production on Sun Sep ::
Copyright (c) Oracle Corporation All rights reserved
DBVERIFY Verification starting : FILE = usersdbf
Page is marked corrupt
***
Corrupt block relative dba: xc (file block )
Bad check value found during dbv:
Data in bad block
type: format: rdba: xc
last change scn: xab seq: x flg: x
consistency value in tail: xb
check value in block header: x computed block checksum: xe
spare: x spare: x spare: x
***
DBVERIFY Verification complete
Total Pages Examined :
Total Pages Processed (Data) :
Total Pages Failing (Data) :
Total Pages Processed (Index):
Total Pages Failing (Index):
Total Pages Processed (Other):
Total Pages Processed (Seg) :
Total Pages Failing (Seg) :
Total Pages Empty :
Total Pages Marked Corrupt :
Total Pages Influx :
全表扫描此时出现ORA错误
重新启动数据库以后执行全表扫描此时错误出现:
SQL> startup force;
ORACLE instance started
Total System Global Area bytes
Fixed Size bytes
Variable Size bytes
Database Buffers bytes
Redo Buffers bytes
Database mounted
Database opened
SQL> select count(*) from bbed;
select count(*) from bbed
*
ERROR at line :
ORA: ORACLE data block corrupted (file # block # )
ORA: data file : /opt/oracle/oradata/conner/usersdbf
SQL>
以上方法仅供测试使用
