A hardware based system that is capable of handling the RAID subsystem independent of the host by sending across just a single disk per RAID array to the host. This way it is not mandatory for the host to be aware of the RAID sub-systems.
Controller based hardware solution for a controller based RAID solution is an apt example for this. The benefit of this as against an external SCSI--SCSI RAID subsystem is that the controller is capable of spanning RAID subsystem above multiple SCSI channels. This eliminates the restraining factor external RAID solutions have which is the transfer rate over the SCSI bus.
External hardware solution (SCSI--SCSI RAID): All RAID handling “intelligence” is stimulated by an external RAID box into a controller that is available in the external disk subsystem and the whole subsystem is linked to the host via a normal SCSI controller that looks like a single or multiple disks to the host.
