HP Dc7700 Redundant Array of Independent Disks (RAID) on HP Compaq dc7700 and - Page 9

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Table 5

RAID 5 with 3 hard drives (Parity)

In the previous table, each “Data Segment x” represents a strip. A stripe is made with strip “Data Segment

x”, “Data Segment y” and strip “Parity for x and y.”

Notice that the strip “Parity for x and y” is used to

store the required information to recreate the data if any one of the RAID volume members is compro-

mised.

To better illustrate the concept of RAID 5 (parity based RAID), the following figure shows how a sequence

of data “ABCD...” is stored in a RAID 5. In this example, each letter represents a segment or strip. The fig-

ure shows how the various pieces of the information go to different hard drives, hence if any one member

of the RAID 5 fails, the information from all members is not lost.

Figure 4

RAID 5 with three hard drives

First Disk

Second Disk

Third Disk

Data Segment 1

Data Segment 2

Parity for 1 and 2

Data Segment 3

Parity for 3 and 4

Data Segment 4

Parity for 5 and 6

Data Segment 5

Data Segment 6

Data Segment 7

Data Segment 8

Parity for 7 and 8

Data Segment 9

Parity for 9 and 10

Data Segment 10

Parity for 11 and 12

Data Segment 11

Data Segment 12

Data Segment 13

Data Segment 14


Data Segment 15


Data Segment 16


Data Segment 17

Data Segment 18

HP Dc7700 Redundant Array of Independent Disks (RAID) on HP Compaq dc7700 and - Page 9

First Disk, Second Disk, Third Disk

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