Chart illustrating the probability of a two drive failure in a RAID 10 (striped RAID 1 sets) configuration being a mirrored pair.
In other words, if any two drives fail simultaneously, the chart below illustrates the probability that the two drives are a mirrored pair (RAID 1) of each other, thus resulting in complete loss of data.
X axis = Total number of drives in RAID 10.
Disks Probability Of A Two Disk Failure Both Being In Any Sub-Array (Mirrored Pair)
4 33.3%
6 20.0%
8 14.3%
10 11.1%
12 9.1%
14 7.7%
16 6.7%
In other words, if any two drives fail simultaneously, the chart below illustrates the probability that the two drives are a mirrored pair (RAID 1) of each other, thus resulting in complete loss of data.

X axis = Total number of drives in RAID 10.
Disks Probability Of A Two Disk Failure Both Being In Any Sub-Array (Mirrored Pair)
4 33.3%
6 20.0%
8 14.3%
10 11.1%
12 9.1%
14 7.7%
16 6.7%
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