This is a text description of archreda.gif.  

This figure illustrates what will be discussed in this chapter. It 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.