Disk Array Types; Enclosure Management - LSI MegaRAID SCSI 320-2 RAID Controller Series 518 Hardware Manual

2.3.14 Disk Array Types

2.3.15 Enclosure Management

Table 2.4 describes the RAID disk array types.
Table 2.4 Disk Array Types
Type Description
Software- The array is managed by software running in a host computer
Based 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 via a SCSI adapter in the host.
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 parity and handle other RAID functions. A bus-based
controller can transfer data at the speed of the host bus but is
limited to the bus it is designed for. MegaRAID SCSI 320-2
resides on a PCI bus, which can handle data transfer at up to
132 Mbytes/s. With MegaRAID SCSI 320-2, the channel can
handle data transfer rates up to 320 Mbytes/s per SCSI
channel.
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 can be 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.
RAID Overview
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
2-11