RAID Overview

RAID is an important storage system for industrial applications where voluminous data needs to be stored. Redundant array of independent disks (RAID) is a system of multiple hard drives. The system allows multiple hard disks to share one or more RAID controllers. This results in a single, fast, and a large hard disk drive. On the whole RAID system enhances the performance by storing the same data in different locations of hard disks. To interface multiple disk drives RAID internal bus systems, standalone modules, computer boards, or controllers are used. Special protocols are also required to control RAID systems.

RAID characteristics

The major advantage of RAID system is to combine multiple low cost devices through existing technology. This gives the advantage of greater capacity, data reliability, speed, and increased throughput. Number o hard disks in an array can differ among various RAID systems. Therefore maximum capacity, data transfer rate, and operating temperatures also vary. Temperature control involves cooling fans and temperature sensors. Some RAID systems contain hot-swappable hard disks.

RAID Mounting Styles

In mounting options RAID arrays can be panel or rack mounted. They can also be attached and detached to the chassis. Integrated RAID dusk arrays are hard wired, soldered, or permanently attached to chassis. Furthermore Standalone RAID systems are also available. A RAID system may contain an LED to indicate hard disk read or write operations. Others contain buzzers or email options.

RAID Interfaces

RAID systems offer two types of interfaces. One is disk channel interface and other is host interface.

RAID Disk Channel Interface

Disk channel interfaces include ATA / IDE, SCSI variants, or fiber channel. ATA / IDE options include parallel ATA, Serial ATA, ATA - 2, ATA – 3, ATA / 100, ATA / 66, and Ultra ATA. Fiber channel Interface uses optical fibers for connection. This requires a high bandwidth. Fiber channel interface operates on a SCSI compatible serial data transfer architecture. FC-AL (fiber channel arbitrated loop) is the most prominent architecture. FC-AL offers data transfer rates of 100 Mega Bytes per second (MBps) in full duplex mode.

RAID Host Interface

Host Interface options for RAID systems include SCSI, Fiber Channel, USB (universal serial bus), FireWire®, and PCI (peripheral component interconnect). PCI variants offer 32-bit PCI and 64-bit PCI. FireWire is also known as IEEE 1394 and a registered trademark of Apple Computer, Inc.

RAID Implementation

RAID can be implemented in three ways. These include custom software, dedicated hardware, or partial hardware and partial software implementations.