HP Dc7700 Redundant Array of Independent Disks (RAID) on HP Compaq dc7700 and - Page 9
First Disk, Second Disk, Third Disk
UPC - 882780715318
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Table 5 RAID 5 with 3 hard drives (Parity) First Disk Data Segment 1 Data Segment 3 Parity for 5 and 6 Data Segment 7 Data Segment 9 Parity for 11 and 12 Data Segment 13 Data Segment 15 Parity for 17 and 18 Second Disk Data Segment 2 Parity for 3 and 4 Data Segment 5 Data Segment 8 Parity for 9 and 10 Data Segment 11 Data Segment 14 Parity for 15 and 16 Data Segment 17 Third Disk Parity for 1 and 2 Data Segment 4 Data Segment 6 Parity for 7 and 8 Data Segment 10 Data Segment 12 Parity for 13 and 14 Data Segment 16 Data Segment 18 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 compromised. 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 figure 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 9