FastTrak SX4300, SX8300 User Manual
About Dual Data Redundancy
One unique (though rarely occurring) feature of RAID 10 is dual fault tolerance. In some cases, two drives can fail simultaneously and still maintain the integrity of data. There are six combinations in which two drives can fail. The FastTrak SX4300 or SX8300 card protects your data array in four of those cases. Assume the drives are configured as follows:
•CH indicates channels on the FastTrak Controller card.
•A/B indicates which striped pair the drive belongs to.
•1/2 indicates which part of stripe data.
CH1 | CH2 | CH3 | CH4 |
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Drive A1 | Drive A2 | Drive B1 | Drive B2 |
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Under RAID 10, the array maintains data integrity if any 1, 2 combination survives.
| Failed | Logical Drive |
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Event | Drives | Status | Why? |
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1 | A1/A2 | Functional | B1/B2 retain integrity |
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2 | B1/B2 | Functional | A1/A2 retain integrity |
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3 | A1/B2 | Functional | B1/A2 retain integrity |
4 | B1/A2 | Functional | A1/B2 retain integrity |
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5 | A1/B1 | Offline | B2/A2 contain only half the data |
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6 | B2/A2 | Offline | A1/B1 contain only half the data |
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