This is a text description of archred3.gif.  

This figure shows LGWR writing to an active online redo log file (LOG5), while
multiple archive log processes (in this illustration ARC0, ARC1, and ARC2) are
working to write filled online redo log files (LOG2, LOG3, and LOG4) to
multiplexed (in this case 2) archived redo log destinations.  Each instance of
ARCn is shown to be responsible for only one online redo log file (at a time).