How often is your data burned to dvd\cd and moved offsite.  Or is this not important.  I wish i could utilized a 500GB storage device for a month of backups.  One of the 100+ servers I monitor\maintain has a 2TB backup drive for a single full backup.  With something that size we look to replication, tape library and offsite storage.  Everyday the backups are shipped off site.  Obviously it is a function of scale but there are 10MB databases that are far more important than 2TB db's.  Another good question is security.  Tapes can be encrypted, password protected, and are software specific often times.  This could be important depending what is in that db.  On some of my smaller sites we can leverage a single tape for everything on the server which is very nice.  I would also bet that tape media will outlast the dvd\cd media if stored properly.  On the otherhand dvd\cd will withstand the elements better.   Just some food for though.