Toshiba Magnia 560S - Manual (Page 37)

RAID Overview
Introduction to RAID
19
Disk Array Types
Table 2.6 describes the RAID disk array types.
Table 2.6 Disk Array Types
Type Description
Software-Based The array is managed by software running in a host computer
using the host CPU bandwidth. The disadvantages associated
with this method are the load on the host CPU and the need for
different software for each operating system.
SCSI-to-SCSI The array controller resides outside of the host computer and
communicates with the host through a SCSI adapter in the host.
The array management software runs in the controller. It is
transparent to the host and independent of the host operating
system. The disadvantage is the limited data transfer rate of the
SCSI channel between the SCSI adapter and the array controller.
Bus-Based The array controller resides on the bus (for example, a PCI or
EISA bus) in the host computer and has its own CPU to generate
the parity and handle other RAID functions. A bus-based
controller can transfer data at the speed of the host bus (PCI,
ISA, EISA, VL-Bus) but is limited to the bus it is designed for.
RAID Controller Kit-G resides on a PCI bus, which can handle
data transfer at up to 132 MB/s. With RAID Controller Kit-G,
the channel can handle data transfer rates up to 320 MB/s per
SCSI channel.
Enclosure Management
Enclosure management is the intelligent monitoring of the disk subsystem by software
and/or hardware.
The disk subsystem can be part of the host computer or separate from it. Enclosure
management helps you stay informed of events in the disk subsystem, such as a drive or
power supply failure. Enclosure management increases the fault tolerance of the disk
subsystem.