I am studying for my second test in Data Administration and I have a question. I am reading about redo log files and Archiving. Why do you have both. It seems to me that they are the same except for the fact that the archive files don't get over written. When the redo log file is written to the online files and a checkpoint is called it seems to me that the changes are in the datafiles and if the database crashes the info is already in the datafiles. Why do you need the archive logs??