1、在创建新的undo tablesapce “undotbs2”后，删除旧的undo tablespace
15:12:49 SYS@ prod>ALTER tablespace undotbs1 offline immediate;
Tablespace altered.
Elapsed: 00:00:00.15
报以下错误：
15:12:59 SYS@ prod>drop tablespace undotbs1 including contents and datafiles;
drop tablespace undotbs1 including contents and datafiles
*
ERROR at line 1:
ORA-01548: active rollback segment '_SYSSMU1_3780397527$' found, terminate dropping tablespace
Elapsed: 00:00:00.05
2、通过spfile生成pfile
15:13:08 SYS@ prod>create pfile from spfile;
File created.
Elapsed: 00:00:00.11
15:14:12 SYS@ prod>shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
在initprod.ora 文件加入以下隐含参数：
_offline_rollback_segments=(_SYSSMU10_3550978943$,_SYSSMU9_1424341975$,_SYSSMU8_2012382730$,_SYSSMU7_3286610060$,_SYSSMU6_2443381498$,_SYSSMU5_1527469038$,_SYSSMU4_1152005954$,_SYSSMU3_2097677531$,_SYSSMU2_2232571081$,_SYSSMU1_3780397527$)
3、重新启动database，并删除旧的undo tablespace
[oracle@rh6 dbs]$ sqlplus '/as sysdba'
SQL*Plus: Release 11.2.0.1.0 Production on Thu Jun 26 16:32:49 2014
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
16:32:49 SYS@ prod>create spfile from pfile;
File created.
Elapsed: 00:00:00.04
16:32:52 SYS@ prod>startup
ORACLE instance started.
Total System Global Area 835104768 bytes
Fixed Size 2217952 bytes
Variable Size 775948320 bytes
Database Buffers 54525952 bytes
Redo Buffers 2412544 bytes
Database mounted.
Database opened.
16:33:06 SYS@ prod>drop tablespace undotbs1 including contents and datafiles;
Tablespace dropped.
Elapsed: 00:00:00.59
16:33:17 SYS@ prod>shutdown immediate；
在pfile 删除_offline_rollback_segments参数；
16:33:56 SYS@ prod>create spfile from pfile;
File created.
Elapsed: 00:00:00.05
16:33:59 SYS@ prod>startup
ORACLE instance started.
Total System Global Area 835104768 bytes
Fixed Size 2217952 bytes
Variable Size 775948320 bytes
Database Buffers 54525952 bytes
Redo Buffers 2412544 bytes
Database mounted.
Database opened.
16:34:17 SYS@ prod>select count(*) from scott.emp;
COUNT(*)
----------
14
Elapsed: 00:00:00.05
16:34:20 SYS@ prod>select tablespace_name,status from dba_tablespaces;
TABLESPACE_NAME STATUS
------------------------------ ---------
SYSTEM ONLINE
SYSAUX ONLINE
TEMP ONLINE
USERS ONLINE
UNDOTBS2 ONLINE
EXAMPLE ONLINE
TBS1 ONLINE
7 rows selected.
Elapsed: 00:00:00.06
16:34:28 SYS@ prod>
@至此，undo tablespace 被正常删除！