SQL> create rollback segment rbs06 tablespace rbs storage (initial 8388608 next 8388608 maxextents unlimited optimal 209715200);
create rollback segment rbs06 tablespace rbs storage (initial 8388608 next 8388608 maxextents unlimited optimal 209715200)
*
ERROR at line 1:
ORA-01593: rollback segment optimal size (25600 blks) is smaller than the computed initial size (40960 blks)


SQL> create rollback segment rbs06 tablespace rbs storage (initial 8388608 next 8388608 maxextents unlimited);

Rollback segment created.

SQL> alter rollback segment rbs06 storage (optimal 209715200);

Rollback segment altered.