IBM 81Y Computer Hardware User Manual


 
Using IBM ServeRAID 121
level-1, the data is mirrored, and the capacity of the logical drive is 50% of the array
capacity of the grouping of physical drives in the array.
RAID level-1E requires a minimum of three drives and, depending upon the level of
firmware and the stripe-unit size, supports a maximum of eight or 16 drives.
The following illustration is an example of an Enhanced RAID level-1 logical drive.
You start with three physical drives.
Create an array using the physical drives.
Then, create a logical drive within that array.
The data is striped across the drives, creating blocks. Notice that the stripe labeled
is the data stripe and the stripe labeled is the mirror (that is, the copy) of the
preceding data stripe. Also notice that each block on the mirror stripe is shifted one
drive.
1 2 3
3 1 2
4 5 6
6 4 5
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