I tried exp utility to dump all database. Looks like this exports only the last version of data skipping undo log. Using flashback queries I see:
01466. 00000 - "unable to read data - table definition has changed" *Cause: Query parsed after tbl (or index) change, and executed w/old snapshot
What I'm trying to do is to capture db changes, make backup for later use with the ability to flashback to timestamp.
With rman backup I have similar situation:
ORA-01555: snapshot too old: rollback segment number 3 with name "_SYSSMU3_2472002983$" too small 01555. 00000 - "snapshot too old: rollback segment number %s with name \"%s\" too small" *Cause: rollback records needed by a reader for consistent read are overwritten by other writers`.
Update: I managed to do what I needed only by increasing undo retention and direct copying of data files and control file modification on cloned instance.