How to simulate block corruption with BBED?

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 Oracle-l 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 Oracle10g 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


1.创建测试表

[oracle@jumper conner]$ sqlplus "/ as sysdba"
SQL*Plus: Release 9.2.0.4.0 - Production on Sun Sep 11 19:59:27 2005
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
SQL> create table bbed tablespace users as select * from dba_tables;
Table created.
SQL> select count(*) from bbed;
  COUNT(*)
----------
       523
SQL> col segment_name for a10
SQL> select segment_name,file_id,block_id from dba_extents where segment_name='BBED';
SEGMENT_NA    FILE_ID   BLOCK_ID
---------- ---------- ----------
BBED                3          9
BBED                3         17
BBED                3         25
SQL> select count(*) from bbed;
  COUNT(*)
----------
       523

2.创建BBED参数文件等

[oracle@jumper conner]$ more filelist.txt 
         1 /opt/oracle/oradata/conner/system01.dbf   440401920
         2 /opt/oracle/oradata/conner/undotbs01.dbf  104857600
         3 /opt/oracle/oradata/conner/users01.dbf     27262976
[oracle@jumper conner]$ more par.bbd 
blocksize=8192
listfile=filelist.txt
mode=edit

3.使用BBED

[oracle@jumper conner]$ bbed parfile=par.bbd 
Password: 
BBED: Release 2.0.0.0.0 - Limited Production on Sun Sep 11 20:01:01 2005
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
************* !!! For Oracle Internal Use only !!! ***************
BBED> set file 3
        FILE#           3
BBED> show
        FILE#           3
        BLOCK#          1
        OFFSET          0
        DBA             0x00c00001 (12582913 3,1)
        FILENAME        /opt/oracle/oradata/conner/users01.dbf
        BIFILE          bifile.bbd
        LISTFILE        filelist.txt
        BLOCKSIZE       8192
        MODE            Edit
        EDIT            Unrecoverable
        IBASE           Dec
        OBASE           Dec
        WIDTH           80
        COUNT           512
        LOGFILE         log.bbd
        SPOOL           No