undo segments succeed rollback segments.
If you use undo segments you'll don't need rollback segments  anymore.

Hth

Basically, yes. As I understand it, one merely specifies an undo
tablespace of sufficient size and lets oracle get on with it. Parameters
are UNDO_MANAGEMENT=AUTO and UNDO_TABLESPACE. Forget rollback segments.

It's useful to look up UNDO_RETENTION too.

And btw, these days it's probably a good idea to use an spfile rather
than an init.ora.

Palooka

You really should get out more.