www.whatis.com ( http://searchstorage.techtarget.com/sDefinition/0,,sid5_gci214332,00.html ) gives a pretty decent description. If you want a mind expanding experience, as EMC about their RAID levels... There are three variables that raid addresses - write performance, read performance, and reliability. Oh, and the group already knows this, but it doesn't hurt repeating - RAID is not a replacement for backups. __________________________________________________ Do You Yahoo!? Yahoo! Greetings - Send FREE e-cards for every occasion! http://greetings.yahoo.com