Rebalance/move or strink oracle undotablespace
You can simply create a new undo Ts and drop the old one .

show parameter undo

NAME TYPE VALUE



undo_management string AUTO

undo_retention integer 900

undo_tablespace string UNDOTBS1

SQL&gt; CREATE UNDO TABLESPACE undotbs2 DATAFILE '+DATA_NEWPATH' SIZE 100M AUTOEXTEND ON;

http://www.oracle-base.com/articles/9i/AutomaticUndoManagement.php

SQL&gt; alter system set undo_tablespace=undotbs2;

After that can drop UNDOTBS1. Take a look here for more information.

Regards