ADAC Ultra2 S466 – Host-Based RAID Solution
RAID products are either:
∙host-based or
∙SCSI-to-SCSI.
The ADAC Ultra2 S466 controller is a host-based RAID solution. ADAC Ultra2 S466 is a PCI adapter card that is installed in any available PCI expansion slot in a host system.
Host-BasedA host-based RAID product puts all of the RAID intelligence on an adapter card that is installed in a network server. A host-based RAID product provides the best performance. ADAC Ultra2 S466 is part of the file server, so it can transmit data directly across the computer’s buses at data transfer speeds up to 132 MB/s.
The available sequential data transfer rate is determined by the following factors:
∙the sustained data transfer rate on the motherboard PCI bus,
∙the sustained data transfer rate on the i960RP PCI to PCI bridge,
∙the sustained data transfer rate of the SCSI controller,
∙the sustained data transfer rate of the SCSI devices,
∙the number of SCSI channels, and
∙the number of SCSI disk drives.
Host-based solutions must provide operating system- specific drivers.
SCSI-to-SCSIA SCSI-to-SCSI RAID product puts the RAID intelligence inside the RAID chassis and uses a plain SCSI Host Adapter installed in the network server. The data transfer rate is limited to the bandwidth of the SCSI channel. A SCSI-to-SCSI RAID product that has two wide SCSI channels that operate at speeds up to 80 MB/s must squeeze the data into a single wide SCSI (40 MB/s) channel back to the host computer.
In SCSI-to-SCSI RAID products, the hard drive subsystem uses only a single SCSI ID, which allows you to connect multiple drive subsystems to a single SCSI controller.
