RAID 5 may be a higher level than RAID 1, but that does not mean that RAID 5 is superior to RAID 1 in every way. A RAID level is just a technique being used and does not correspond to any hierarchy. When looking at a RAID controller, it is important to understand what the benefits are to each RAID level as most controllers only support a subset of levels. Originally, only RAID 1 through RAID 5 were defined but since the 1988 Berkeley paper was written, other levels have been added.