One of the big requirements in any serious data storage system is RAID, or a Redundant Array of Independent Disks. The I in the definition once meant Inexpensive, but that's relative. A one-petabyte RAID array costs far less than a single one-petabyte disk, but it is still rather expensive. A RAID system splits data between the drives to improve performance or reliability. RAID can work in either hardware or software.
Hardware vs. Software RAID
FreeBSD supports both hardware and software RAID. Hardware RAID is managed by the SCSI controller, and host adapters that provide RAID are called RAID controllers. When you run RAID in hardware, the controller handles all the computations of how to arrange data on the hard drives. Most hardware RAID ...