physical structures consist of three core database files
1> datafile... used to store the actual data in the database.
2> redologfile.. stores all changes which are to made in the database. oracle
keeps two redolog files in the db. in separate disk so that during disk failure
we can recover the database.
3> controlfile.. which stores the physical location of the datafile stores the scn for each and every update in datafile and redolog file.. we can also recover the database from control file also....