The parity data is distributed across all the physical disks in the system. If a single physical disk fails, it can be rebuilt from the parity and the data on the remaining physical disks. RAID level 5 combines distributed parity with disk striping, as shown in Figure A-3. Parity provides redundancy for one physical disk failure without duplicating the contents of entire physical disks.

RAID 6 combines dual distributed parity with disk striping. This level of parity allows for two disk failures without duplicating the contents of entire physical disks.

Figure A-3. Example of Distributed Parity (RAID 5)

Stripe element 1

Stripe element 2

Stripe element 3

Stripe element 4

Stripe element 5

Parity (1–5)

Stripe element 7

Stripe element 8

Stripe element 9

Stripe element 10

Parity (6–10)

Stripe element 6

Stripe element 13

Stripe element 14

Stripe element 15

Parity (11–15)

Stripe element 11

Stripe element 12

Stripe element 19

Stripe element 20

Parity (16–20) Stripe element 16

Stripe element 17

Stripe element 18

Stripe element 25

Parity (21–25)

Stripe element 21

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Stripe element 23

Stripe element 24

Parity (26–30)

Stripe element 26

Stripe element 27

Stripe element 28

Stripe element 29

Stripe element 30

NOTE: Parity is distributed across multiple physical disks in the disk group.

Figure A-4. Example of Dual Distributed Parity (RAID 6)

Stripe element 1

Stripe element 2

Stripe element 3

Stripe element 4

Parity (1–4)

Parity (1–4)

Stripe element 5

Stripe element 6

Parity (5–8)

Parity (5–8)

Stripe element 7

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Parity (9–12)

Parity (9–12)

Stripe element 9

Stripe element 10

Stripe element 11

Stripe element 12

Stripe element 13

Stripe element 14

Parity (13–16)

Parity (13–16)

Stripe element 15

Stripe element 16

NOTE: Parity is distributed across all disks in the array.

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Appendix: RAID Description

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Image 132
Dell H710P, H310, H810 Figure A-3. Example of Distributed Parity RAID, Figure A-4. Example of Dual Distributed Parity RAID

H310, H710, H710P, H810 specifications

Dell offers a range of storage controller technologies, notably the H810, H710, H710P, and H310, which cater to different enterprise needs. These controllers are designed to support various storage configurations, enhancing overall system performance and reliability.

The Dell H810 is a high-performance PCIe 3.0 RAID controller that supports up to eight internal drives and is particularly suited for demanding workloads. It features advanced RAID levels including RAID 0, 1, 5, 6, 10, 50, and 60, providing flexibility for various data protection strategies. The H810 also supports up to 32TB of storage capacity, making it suitable for environments that require substantial data management capabilities.

The H710 is another powerful RAID controller, widely recognized for its balance of performance and cost-efficiency. It features 1GB of cache memory, which aids in accelerating read and write operations. The H710 supports the same RAID levels as the H810 and allows for up to 512MB of non-volatile memory. This ensures data integrity even in the event of a power failure, making it reliable for critical applications.

The H710P is an enhanced version of the H710, with a significant upgrade in its cache capabilities. It offers 2GB of battery-backed cache memory, further enhancing data processing speeds and improving responsiveness. The H710P is ideal for intensive workloads and virtualization, where rapid access to data is essential. This controller also includes features such as RAID storage pooling, intelligent data tiering, and support for multiple virtual disks.

Finally, the H310 is a cost-effective option for small to medium-sized businesses or those with less demanding storage requirements. It offers similar RAID support as the higher-end controllers but operates with a simpler architecture. The H310 features 512MB of cache, providing sufficient performance for regular workloads without the additional complexities of more advanced controllers.

In summary, Dell's H810, H710, H710P, and H310 storage controllers each serve distinct purposes, providing various features, technologies, and performance characteristics tailored to different business needs. From high-capacity storage solutions to user-friendly setups, Dell’s offerings ensure that organizations can efficiently manage their data storage requirements.