Pay no attention to the previous answer. It is not correct.
If you do a cold backup, the database is not running (you have done a
shutdown). You backup up datafiles, control files and archive logs
(not online redo logs).
If you lose the entire machine/disk subsystem and restore everything
you backed up, you will be able to recover to the point of the last
archive log that you have.
When you issue the recover command you tell oracle you are using a
backup control file. Thus, you will be able to roll through all the
archive logs you have from the point of the last backup. You will
lose what was in the current online redo logs (not yet archived).
You will have to open the database with the resetlogs option.
