Most publications discussing RAID start with describing the different RAID levels .
As you probably know, I like to be different. Well, not just for the sake of being different, but where it makes sense to do so. In this case, I think it makes sense to understand the different concepts and issues that underlie RAID before we go to discussing the different levels. I hope that doing this will not only give you the foundation necessary to understand various design issues and concepts in RAID applications, but will frame the various issues that differentiate RAID levels and make them easier to understand as well. In this section I start off by describing the general concepts that define what RAID is about.