ZBDBA@orcl11g>select * from zbdba;
select * from zbdba
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 3, block # 1449)
ORA-01110: data file 3: '/opt/oracle/oradata/orcl11g/undotbs01.dbf'
这里是事务正在执行，但是数据库直接以abort方式关机，并且对应的回滚段损坏
当然这里其实不需要bbed，只需要用_offline_rollback_segments 隐含参数标记对应的回滚段，然后使用drop rollback segment 该回滚段即可
这里使用bbed目的是在于研究undo回滚段的状态存于何处以及如何修改
这里我们创建另外一个undo表空间，并且切换到该表空间
ZBDBA@orcl11g>create undo tablespace undotbs02 datafile '/opt/oracle/oradata/orcl11g/undotb02.dbf' size 100m; Tablespace created. ZBDBA@orcl11g>alter system set undo_tablespace=undotbs02; System altered. ZBDBA@orcl11g>show parameter undo NAME TYPE VALUE ------------------------------------ ---------------------- ------------------------------ undo_management string AUTO undo_retention integer 900 undo_tablespace string UNDOTBS02我们查看回滚段的状态，发现即使切换了，还有一个回滚段处于online状态，因为这个回滚段上面还存在需要恢复的数据，但是这个回滚段已经被损坏，无法进行恢复。那么我们只能将其删除。
ZBDBA@orcl11g>select segment_name,tablespace_name,status from dba_rollback_segs; SEGMENT_NAME TABLESPACE_NAME STATUS ------------------------------ -------------------- ------------------------------------------------------------ SYSTEM SYSTEM ONLINE _SYSSMU10_3550978943$ UNDOTBS1 ONLINE _SYSSMU9_1424341975$ UNDOTBS1 OFFLINE _SYSSMU8_2012382730$ UNDOTBS1 OFFLINE _SYSSMU7_3286610060$ UNDOTBS1 OFFLINE _SYSSMU6_2443381498$ UNDOTBS1 OFFLINE _SYSSMU5_1527469038$ UNDOTBS1 OFFLINE _SYSSMU4_1152005954$ UNDOTBS1 OFFLINE _SYSSMU3_2097677531$ UNDOTBS1 OFFLINE _SYSSMU2_2232571081$ UNDOTBS1 OFFLINE _SYSSMU1_3780397527$ UNDOTBS1 OFFLINE _SYSSMU20_3705739785$ UNDOTBS02 ONLINE _SYSSMU19_3920348761$ UNDOTBS02 ONLINE _SYSSMU18_2539622763$ UNDOTBS02 ONLINE _SYSSMU17_178842559$ UNDOTBS02 ONLINE _SYSSMU16_3035903491$ UNDOTBS02 ONLINE _SYSSMU15_444141832$ UNDOTBS02 ONLINE _SYSSMU14_3021863913$ UNDOTBS02 ONLINE _SYSSMU13_3717211136$ UNDOTBS02 ONLINE _SYSSMU12_3182721254$ UNDOTBS02 ONLINE _SYSSMU11_3909920883$ UNDOTBS02 ONLINE通过以下可以看到不同的数字对应不同的状态：
undo segment 的状态：
1表示offline并且被删除
2 表示offline
3 表示online
4 未知
5 表示need recovery
SYS@orcl11g>select name,status$ from undo$; NAME STATUS$ ------------------------------------------------------------ ---------- SYSTEM 3 _SYSSMU1_3780397527$ 2 _SYSSMU2_2232571081$ 2 _SYSSMU3_2097677531$ 2 _SYSSMU4_1152005954$ 2 _SYSSMU5_1527469038$ 2 _SYSSMU6_2443381498$ 2 _SYSSMU7_3286610060$ 2 _SYSSMU8_2012382730$ 2 _SYSSMU9_1424341975$ 2 _SYSSMU10_3550978943$ 3 _SYSSMU11_3909920883$ 3 _SYSSMU12_3182721254$ 3 _SYSSMU13_3717211136$ 3 _SYSSMU14_3021863913$ 3 _SYSSMU15_444141832$ 3 _SYSSMU16_3035903491$ 3 _SYSSMU17_178842559$ 3 _SYSSMU18_2539622763$ 3 _SYSSMU19_3920348761$ 3 _SYSSMU20_3705739785$ 3强制将该回滚段offline，发现还是无法删除：
SYS@orcl11g>alter rollback segment "_SYSSMU10_3550978943$" offline; Rollback segment altered. SYS@orcl11g>drop tablespace UNDOTBS1; drop tablespace UNDOTBS1 * ERROR at line 1: ORA-30013: undo tablespace 'UNDOTBS1' is currently in use此时，我们关闭数据库使用bbed更改该回滚段的状态：
在数据库启动的时候，我们可以是oradebug 10046事件追踪，通过trace文件分析:
PARSING IN CURSOR #2 len=142 dep=1 uid=0 oct=3 lid=0 tim=1414654507002840 hv=361892850 ad=