undo tablespace problem , urgent plz?

[madhugp]

to reduce the size of my undo tablespace ' UNDOTBS1' I used the following method..

CREATED ANOTHER TABLESPACE UNDOTBS2;

ALTER SYSTEM SET UNDO TABLESPACE = 'UNDOTBS2';
ALTERED SUCCESSFULLY.

NOW I WANT TO DROP THE FIRST TABLESPACE , BUT
WE SHOULD MAKE IT OFFLINE FIRST.

ALTER TABLESPACE UNDOTBS1 OFFLINE;

GIVES ORA-30042 CANNOT MAKE OFFLINE

WHY HAPPEND THIS. PLZ SUGGEST?

[davey23uk]

if its urgent call oracle support, thats what they are there for

[mahajanakhil198]

One thing that seems to me is that the previous undo tablespace still contains active undo segments that may be referred in future. Isn't it?

Y dont u check using v$rollstat and v$rollname

SELECT a.name,b.status
FROM v$rollname a, v$rollstat b
WHERE a.name IN ( SELECT segment_name
FROM dba_segments)
AND a.usn = b.usn
/