2.3.14 Disk Array Types
Table 2.4 describes the RAID disk array types.
Table 2.4 | Disk Array Types | |
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Type |
| Description |
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|
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 |
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| for different software for each operating system. |
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| |
SCSI to SCSI | The array controller resides outside of the host computer and | |
|
| communicates with the host through a SCSI adapter in the |
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| 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 |
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| array controller. |
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|
|
| The array controller resides on the bus (for example, a PCI or | |
|
| EISA bus) in the host computer and has its own CPU to |
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| generate the parity and handle other RAID functions. A bus- |
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| based controller can transfer data at the speed of the host bus |
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| (PCI, ISA, EISA, |
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| for. MegaRAID SCSI |
|
| handle data transfer at up to 132 Mbytes/s. With MegaRAID |
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| SCSI |
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| 320 Mbytes/s per SCSI channel. |
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|
|
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.
RAID Overview |
Copyright © 2002 by LSI Logic Corporation. All rights reserved.