The latest hard disks are manufactured in sizes as large as 4TB and they are getting larger every year. In the near future, they will probably reach up to 8TB and even beyond that. Although huge sized hard disks work extremely well, sometimes these may not be enough for certain applications.
The term “RAID” stands for Redundant Array of Independent Disks/Inexpensive Disks. Usually it is suggested that all disks in a particular RAID must be similar in performance and functionality. The experts have designed numerous variations of RAID to meet different requirements. Some of them have been designed for making larger, faster storage solutions and some are for enhanced reliability.