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FastTrak SX4100 User Manual
About Dual Data Redundancy
One unique (though rarely occurring) feature of RAID 10 is dual fault tolerance. In
some cases, two disk drives can fail simultaneously and still maintain the integrity
of data. There are six combinations in which two drives can fail. The FastTrak
SX4100 card protects your data 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.
Under RAID 10, the logical drive maintains data integrity if any 1, 2 combination
survives.
Failed
Event
Drives
1
A1/A2
2
B1/B2
3
A1/B2
4
B1/A2
5
A1/B1
6
B2/A2
CH1
CH2
Drive A1
Drive A2
Logical Drive
Status
Functional
Functional
Functional
Functional
Offline
Offline
CH3
Drive B1
Drive B2
B1/B2 retain integrity
A1/A2 retain integrity
B1/A2 retain integrity
A1/B2 retain integrity
B2/A2 contain only half the data
A1/B1 contain only half the data
38
CH4
Why?
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