LSI MegaRAID SCSI 320-2 RAID Controller Series 518 User Manual download pdf (Page 35)

RAID Overview 2-11

2.3.14 Disk Array Types

Table 2.4 describes the RAID disk array types.

2.3.15 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 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.

Table 2.4 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 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.

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LSI MegaRAID SCSI 320-2 RAID Controller Series 518 User Manual Page 35