undo_management设置与隐含参数*._offline_rollback_segments和*._corrupted_rollback_segments关系

一 环境：
oracle版本：10.2.0.1.0
当前undo表空间：
SQL> show parameter undo;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      AUTO
undo_retention                       integer     900
undo_tablespace                      string      UNDOTBS4
当前系统内的还原表空间：
SQL> select tablespace_name,status from dba_tablespaces where tablespace_name like '%UNDO%';

TABLESPACE_NAME                STATUS
------------------------------ ---------
UNDOTBS4                       ONLINE
当前undo表空间undotbs4的所有回滚段状况如下：
SQL> select * from v$rollname; （查询当前系统活动回滚段）

       USN NAME
---------- ----------------------------------------
         0 SYSTEM
         1 _SYSSMU1$
         2 _SYSSMU2$
         3 _SYSSMU3$
         4 _SYSSMU4$
         5 _SYSSMU5$
         6 _SYSSMU6$
         7 _SYSSMU7$
         8 _SYSSMU8$
         9 _SYSSMU9$
        11 _SYSSMU11$

11 rows selected.

SQL> select segment_id,segment_name,tablespace_name,status from dba_rollback_segs;（ 查询系统内所有回滚段信息）

SEGMENT_ID SEGMENT_NAME                   TABLESPACE_NAME                STATUS
---------- ------------------------------ ------------------------------ ----------------
         0 SYSTEM                         SYSTEM                         ONLINE
         1 _SYSSMU1$                      UNDOTBS4                       ONLINE
         2 _SYSSMU2$                      UNDOTBS4                       ONLINE
         3 _SYSSMU3$                      UNDOTBS4                       ONLINE
         4 _SYSSMU4$                      UNDOTBS4                       ONLINE
         5 _SYSSMU5$                      UNDOTBS4                       ONLINE
         6 _SYSSMU6$                      UNDOTBS4                       ONLINE
         7 _SYSSMU7$                      UNDOTBS4                       ONLINE
         8 _SYSSMU8$                      UNDOTBS4                       ONLINE
         9 _SYSSMU9$                      UNDOTBS4                       ONLINE
        11 _SYSSMU11$                     UNDOTBS4                       ONLINE

11 rows selected.

SQL>
二 测试
当系统有一个还原表空间undotbs4
测试1 undo_management=auto ，用参数*._offline_rollback_segments和*._corrupted_rollback_segments标记当前undo表空间undotbs4的所有段，查询当前oracle所有活动回滚段。
测试2 undo_management=manual ，用参数*._offline_rollback_segments和*._corrupted_rollback_segments标记当前undo表空间undotbs4的所有段，查询当前oracle所有活动回滚段。
当系统有多个还原表空间，undotbs4、undotbs3、undotbs2、undotbs1
测试3 undo_management=auto ，用参数*._offline_rollback_segments和*._corrupted_rollback_segments标记当前undo表空间undotbs4的所有段，查询当前oracle所有活动回滚段。
测试4 undo_management=manual， 用参数*._offline_rollback_segments和*._corrupted_rollback_segments标记当前undo表空间undotbs4的所有段，查询当前oracle所有活动回滚段。

三实验过程
当系统仅有一个还原表空间undotbs4
测试1：
initCRM.ora 内容如下：
*.undo_management='AUTO'
*.undo_tablespace='UNDOTBS4'
*.user_dump_dest='/oracle/app/admin/CRM/udump'
*._offline_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'
*._corrupted_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'

oracle启动过程如下：
SQL> startup pfile='/oracle/app/db1/dbs/initCRM.ora';
ORACLE instance started.
Total System Global Area  322961408 bytes
Fixed Size                  2020480 bytes
Variable Size              83889024 bytes
Database Buffers          230686720 bytes
Redo Buffers                6365184 bytes
Database mounted.
ORA-01092: ORACLE instance terminated. Disconnection forced

告警文件错误信息如下：
Errors in file /oracle/app/admin/CRM/udump/crm_ora_9154.trc:
ORA-30012: undo tablespace 'UNDOTBS4' does not exist or of wrong type
Tue Nov 13 22:13:15 2012
Error 30012 happened during db open, shutting down database
USER: terminating instance due to error 30012
Instance terminated by USER, pid = 9154
ORA-1092 signalled during: ALTER DATABASE OPEN...
总结：库都启动不了，回滚段信息就不要看了。
-------------------------------------------------------------------------------
测试2：
initCRM.ora 内容如下：
*.undo_management='MANUAL'
*.undo_tablespace='UNDOTBS4'
*.user_dump_dest='/oracle/app/admin/CRM/udump'
*._offline_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'
*._corrupted_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'

oracle启动过程如下：
SQL>  startup pfile='/oracle/app/db1/dbs/initCRM.ora';
ORACLE instance started.
Total System Global Area  322961408 bytes
Fixed Size                  2020480 bytes
Variable Size              83889024 bytes
Database Buffers          230686720 bytes
Redo Buffers                6365184 bytes
Database mounted.
Database opened.

当前oracle所有活动回滚段状态如下:
 select segment_id,segment_name,tablespace_name,status from dba_rollback_segs

SEGMENT_ID SEGMENT_NAME                   TABLESPACE_NAME                STATUS
---------- ------------------------------ ------------------------------ ----------------
         0 SYSTEM                         SYSTEM                         ONLINE
         1 _SYSSMU1$                      UNDOTBS4                       OFFLINE
         2 _SYSSMU2$                      UNDOTBS4                       OFFLINE
         3 _SYSSMU3$                      UNDOTBS4                       OFFLINE
         4 _SYSSMU4$                      UNDOTBS4                       OFFLINE
         5 _SYSSMU5$                      UNDOTBS4                       OFFLINE
         6 _SYSSMU6$                      UNDOTBS4                       OFFLINE
         7 _SYSSMU7$                      UNDOTBS4                       OFFLINE
         8 _SYSSMU8$                      UNDOTBS4                       OFFLINE
         9 _SYSSMU9$                      UNDOTBS4                       OFFLINE
        11 _SYSSMU11$                     UNDOTBS4                       OFFLINE

11 rows selected.

SQL> select * from v$rollname;

       USN NAME
---------- ------------------------------
         0 SYSTEM

当系统有多个还原表空间时进行如下测试:
SQL> select tablespace_name,status from dba_tablespaces where  tablespace_name like '%UNDO%';

TABLESPACE_NAME                STATUS
------------------------------ ---------
UNDOTBS1                       ONLINE
UNDOTBS2                       ONLINE
UNDOTBS3                       ONLINE
UNDOTBS4                       ONLINE
SQL> show parameter undo;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      MANUAL
undo_retention                       integer     900
undo_tablespace                      string      UNDOTBS4
----------------------------------------------------------------------------------------------------------
测试3
initCRM.ora 内容如下：
*.undo_management='AUTO'
*.undo_tablespace='UNDOTBS4'
*.user_dump_dest='/oracle/app/admin/CRM/udump'
*._corrupted_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'
*._offline_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'

oracle启动过程如下：
SQL> startup pfile='/oracle/app/db1/dbs/initCRM.ora';
ORACLE instance started.

Total System Global Area  322961408 bytes
Fixed Size                  2020480 bytes
Variable Size              83889024 bytes
Database Buffers          230686720 bytes
Redo Buffers                6365184 bytes
Database mounted.
Database opened.

当前oracle所有活动回滚段状态如下:
SEGMENT_ID SEGMENT_NAME                   TABLESPACE_NAME                STATUS
---------- ------------------------------ ------------------------------ ----------------
         0 SYSTEM                         SYSTEM                         ONLINE
         1 _SYSSMU1$                      UNDOTBS4                       OFFLINE
         2 _SYSSMU2$                      UNDOTBS4                       OFFLINE
         3 _SYSSMU3$                      UNDOTBS4                       OFFLINE
         4 _SYSSMU4$                      UNDOTBS4                       OFFLINE
         5 _SYSSMU5$                      UNDOTBS4                       OFFLINE
         6 _SYSSMU6$                      UNDOTBS4                       OFFLINE
         7 _SYSSMU7$                      UNDOTBS4                       OFFLINE
         8 _SYSSMU8$                      UNDOTBS4                       OFFLINE
         9 _SYSSMU9$                      UNDOTBS4                       OFFLINE
        11 _SYSSMU11$                     UNDOTBS4                       OFFLINE
        12 _SYSSMU12$                     UNDOTBS1                       OFFLINE
        13 _SYSSMU13$                     UNDOTBS1                       OFFLINE
        14 _SYSSMU14$                     UNDOTBS1                       OFFLINE
        15 _SYSSMU15$                     UNDOTBS1                       OFFLINE
        16 _SYSSMU16$                     UNDOTBS1                       OFFLINE
        17 _SYSSMU17$                     UNDOTBS1                       OFFLINE
        18 _SYSSMU18$                     UNDOTBS1                       OFFLINE
        19 _SYSSMU19$                     UNDOTBS1                       OFFLINE
        20 _SYSSMU20$                     UNDOTBS1                       OFFLINE
        21 _SYSSMU21$                     UNDOTBS1                       OFFLINE
        22 _SYSSMU22$                     UNDOTBS2                       OFFLINE
        23 _SYSSMU23$                     UNDOTBS2                       OFFLINE
        24 _SYSSMU24$                     UNDOTBS2                       OFFLINE
        25 _SYSSMU25$                     UNDOTBS2                       OFFLINE
        26 _SYSSMU26$                     UNDOTBS2                       OFFLINE
        27 _SYSSMU27$                     UNDOTBS2                       OFFLINE
        28 _SYSSMU28$                     UNDOTBS2                       OFFLINE
        29 _SYSSMU29$                     UNDOTBS2                       OFFLINE
        30 _SYSSMU30$                     UNDOTBS2                       OFFLINE
        31 _SYSSMU31$                     UNDOTBS2                       OFFLINE
        32 _SYSSMU32$                     UNDOTBS3                       OFFLINE
        33 _SYSSMU33$                     UNDOTBS3                       OFFLINE
        34 _SYSSMU34$                     UNDOTBS3                       OFFLINE
        35 _SYSSMU35$                     UNDOTBS3                       OFFLINE
        36 _SYSSMU36$                     UNDOTBS3                       OFFLINE
        37 _SYSSMU37$                     UNDOTBS3                       OFFLINE
        38 _SYSSMU38$                     UNDOTBS3                       OFFLINE
        39 _SYSSMU39$                     UNDOTBS3                       OFFLINE
        40 _SYSSMU40$                     UNDOTBS3                       OFFLINE
        41 _SYSSMU41$                     UNDOTBS3                       OFFLINE
        42 _SYSSMU42$                     UNDOTBS4                       ONLINE

42 rows selected.

SQL> select * from v$rollname;

       USN NAME
---------- ------------------------------
         0 SYSTEM
        42 _SYSSMU42$
总结:事实上当我们用参数做如下设置时
*._corrupted_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$','_SYSSMU42$'
*._offline_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$','_SYSSMU42$'
启动后，oracle会产生另一个非系统回滚段_SYSSMU43$如下：
SQL> select * from v$rollname;

       USN NAME
---------- ------------------------------
         0 SYSTEM
        43 _SYSSMU43$
  
SQL> select segment_id,segment_name,tablespace_name,status from dba_rollback_segs
  2  ;

SEGMENT_ID SEGMENT_NAME                   TABLESPACE_NAME                STATUS
---------- ------------------------------ ------------------------------ ----------------
         0 SYSTEM                         SYSTEM                         ONLINE
         1 _SYSSMU1$                      UNDOTBS4                       OFFLINE
         2 _SYSSMU2$                      UNDOTBS4                       OFFLINE
         3 _SYSSMU3$                      UNDOTBS4                       OFFLINE
          。。。。。。。。。。。。。。。此处省略数行。。。。。。。。。
        43 _SYSSMU43$                     UNDOTBS4                       ONLINE

43 rows selected.
也就是说当undo_management=auto时，即使用隐含参数_corrupted_rollback_segments和_offline_rollback_segments标记当前undo表空间所有回滚段，数据库启动时oracle也总会创建一个非系统回滚段，直到undo表空间容量耗尽（猜测）
------------------------------------------------------------------------------------------------------------------------------------------------
测试4：
initCRM.ora参数如下
*.undo_management='MANUAL'
*.undo_tablespace='UNDOTBS4'
*.user_dump_dest='/oracle/app/admin/CRM/udump'
*._corrupted_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'
*._offline_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU11$'

oracle启动过程如下：
SQL> startup pfile='/oracle/app/db1/dbs/initCRM.ora';
ORACLE instance started.
Total System Global Area  322961408 bytes
Fixed Size                  2020480 bytes
Variable Size              83889024 bytes
Database Buffers          230686720 bytes
Redo Buffers                6365184 bytes
Database mounted.
Database opened.

当前oracle所有活动回滚段状态如下:
SQL> select segment_id,segment_name,tablespace_name,status from dba_rollback_segs;

SEGMENT_ID SEGMENT_NAME                   TABLESPACE_NAME                STATUS
---------- ------------------------------ ------------------------------ ----------------
         0 SYSTEM                         SYSTEM                         ONLINE
         1 _SYSSMU1$                      UNDOTBS4                       OFFLINE
         2 _SYSSMU2$                      UNDOTBS4                       OFFLINE
         3 _SYSSMU3$                      UNDOTBS4                       OFFLINE
         4 _SYSSMU4$                      UNDOTBS4                       OFFLINE
         5 _SYSSMU5$                      UNDOTBS4                       OFFLINE
         6 _SYSSMU6$                      UNDOTBS4                       OFFLINE
         7 _SYSSMU7$                      UNDOTBS4                       OFFLINE
         8 _SYSSMU8$                      UNDOTBS4                       OFFLINE
         9 _SYSSMU9$                      UNDOTBS4                       OFFLINE
        11 _SYSSMU11$                     UNDOTBS4                       OFFLINE
        12 _SYSSMU12$                     UNDOTBS1                       OFFLINE
        13 _SYSSMU13$                     UNDOTBS1                       OFFLINE
        14 _SYSSMU14$                     UNDOTBS1                       OFFLINE
        15 _SYSSMU15$                     UNDOTBS1                       OFFLINE
        16 _SYSSMU16$                     UNDOTBS1                       OFFLINE
        17 _SYSSMU17$                     UNDOTBS1                       OFFLINE
        18 _SYSSMU18$                     UNDOTBS1                       OFFLINE
        19 _SYSSMU19$                     UNDOTBS1                       OFFLINE
        20 _SYSSMU20$                     UNDOTBS1                       OFFLINE
        21 _SYSSMU21$                     UNDOTBS1                       OFFLINE
        22 _SYSSMU22$                     UNDOTBS2                       OFFLINE
        23 _SYSSMU23$                     UNDOTBS2                       OFFLINE
        24 _SYSSMU24$                     UNDOTBS2                       OFFLINE
        25 _SYSSMU25$                     UNDOTBS2                       OFFLINE
        26 _SYSSMU26$                     UNDOTBS2                       OFFLINE
        27 _SYSSMU27$                     UNDOTBS2                       OFFLINE
        28 _SYSSMU28$                     UNDOTBS2                       OFFLINE
        29 _SYSSMU29$                     UNDOTBS2                       OFFLINE
        30 _SYSSMU30$                     UNDOTBS2                       OFFLINE
        31 _SYSSMU31$                     UNDOTBS2                       OFFLINE
        32 _SYSSMU32$                     UNDOTBS3                       OFFLINE
        33 _SYSSMU33$                     UNDOTBS3                       OFFLINE
        34 _SYSSMU34$                     UNDOTBS3                       OFFLINE
        35 _SYSSMU35$                     UNDOTBS3                       OFFLINE
        36 _SYSSMU36$                     UNDOTBS3                       OFFLINE
        37 _SYSSMU37$                     UNDOTBS3                       OFFLINE
        38 _SYSSMU38$                     UNDOTBS3                       OFFLINE
        39 _SYSSMU39$                     UNDOTBS3                       OFFLINE
        40 _SYSSMU40$                     UNDOTBS3                       OFFLINE
        41 _SYSSMU41$                     UNDOTBS3                       OFFLINE
        42 _SYSSMU42$                     UNDOTBS4                       OFFLINE
        43 _SYSSMU43$                     UNDOTBS4                       OFFLINE

43 rows selected.

SQL> select * from v$rollname;

       USN NAME
---------- ------------------------------
         0 SYSTEM
实验完毕
总结如下：当我们用隐含参数_offline_rollback_segments、_corrupted_rollback_segments处理回滚段某些问题的时候，undo_management=manual为好。