Recover Oracle Undo Tablespace without Backup

Woke up with an issue regarding a Oracle 10.2.0 database on Linux complaining about an Undo file on startup.


sqlplus '/ as sysdba'

SQL*Plus: Release 10.2.0.3.0 - Production on Fri May 22 20:11:07 2015

Copyright (c) 1982, 2006, Oracle.  All Rights Reserved.

Connected to an idle instance.

SQL> startup pfile='init.ora'
ORACLE instance started.

Total System Global Area 2801795072 bytes
Fixed Size                  2075504 bytes
Variable Size            1275069584 bytes
Database Buffers         1509949440 bytes
Redo Buffers               14700544 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 244 - see DBWR trace file
ORA-01110: data file 244: '/test/ORADATATEST/test/test_undo2a.dbf'


SQL> show parameter undo

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      MANUAL
undo_retention                       integer     21600
undo_tablespace                      string      test_UNDO02
SQL>



SQL> drop tablespace test_UNDO02  including contents and datafiles;
drop tablespace test_UNDO02  including contents and datafiles
*
ERROR at line 1:
ORA-01548: active rollback segment '_SYSSMU4$' found, terminate dropping tablespace

 Check for active rollback segments:

 select segment_id, segment_name,status,tablespace_name from dba_rollback_segs where status not in ('ONLINE','OFFLINE');



Set the following parameter in the pfile.



*._offline_rollback_segments=(_SYSSMU4$)


And now try dropping UNDO tablespace again.

drop tablespace test_UNDO02  including contents and datafiles;

Tablespace dropped.

Now create a new UNDO tablespace:

create UNDO tablespace test_UNDO05 datafile '/test/oradata18/test/test_undo05_file1.dbf' size 500m autoextend on next 1m maxsize 1500m;


Tablespace created.



SQL> create UNDO tablespace test_UNDO05 datafile '/test/oradata18/test/test_undo05_file1.dbf' size 500m autoextend on next 1m maxsize 1500m;


Tablespace created.



SQL> startup pfile='inittest.ora'
ORACLE instance started.

Total System Global Area 2801795072 bytes
Fixed Size                  2075504 bytes
Variable Size            1392510096 bytes
Database Buffers         1392508928 bytes
Redo Buffers               14700544 bytes
Database mounted.
Database opened.

All good now.