RAID systems and setup methods thereof are provided. At least a first group of disks is selected to create a RAID 0 architecture. A second group of disks is further selected to create the RAID 0 architecture. The RAID 0 architectures are concatenated. The second group is within the first group, and the disks of the second group are the disks having remnant disk capacity after the RAID 0 architecture of the first group is created. The RAID 0 architectures corresponding to the first and second group are created respectively based on the disk having minimum disk capacity size among the disks of the first and second group.