Uses

Provides high data throughput, especially for large files. Use

 

RAID 5 for transaction processing applications, because each

 

drive can read and write independently. If a drive fails, the

 

MegaRAID SCSI 320-0 uses the parity data to recreate all

 

missing information. Use also for office automation and online

 

customer service that requires fault tolerance. Use for any

 

application that has high read request rates but low write

 

request rates.

 

 

Strong Points

Provides data redundancy and good performance in most

 

environments

 

 

Weak Points

Disk drive performance is reduced if a drive is being rebuilt.

 

Environments with few processes do not perform as well

 

because the RAID overhead is not offset by the performance

 

gains in handling simultaneous processes.

 

 

Drives

3 to 30

 

The MegaRAID SCSI 320-0 controller supports one or two

 

SCSI channels, with up to 15 SCSI devices on each channel.

 

 

Figure 3.3 shows a RAID 5 array with six disk drives.

Figure 3.3 RAID 5 Array

MegaRAID Controller

Note: Parity is distributed

 

across drives in the array.

Data Flow

 

Disk 1

Disk 2

Disk 3

Disk 4

Disk 5

Disk 6

Segment 1

Segment 2

Segment 3

Segment 4

Segment 5

Segment 6

Segment 7

Segment 8

Segment 9

Segment 10

Segment 11

Segment 12

Parity (9–12)

 

Parity (5–8)

 

Parity (1–4)

 

RAID 5

3-5

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