RAID level-1 Enhanced (RAID level-1E) combines mirroring and data striping. This RAID level stripes data and copies of the data across all of the drives in the pool. As with the standard RAID level-1, the data is mirrored, and the capacity of the logical device is 50% of the pool capacity.
RAID level-1E has a similar profile to RAID level-1; it provides data redundancy and high levels of performance, but the storage capacity is diminished. However, RAID level-1E allows a larger number of physical drives to be used.
RAID level-1E requires a minimum of three drives and, depending upon the level of firmware and the stripe size, supports a maximum of 8 or 16 drives.
The following illustration is an example of a RAID level-1E logical device.
Start with three physical drives. | ![]() |
Create a pool using the physical drives. | ![]() |
Then create a logical device within that pool. | ![]() |
The data is striped across the drives,
creating blocks.
Notice that the stripe labeled *is the data stripe and the stripe labeled ** is the copy of the preceding data stripe. Also, notice that each block on the mirror stripe is shifted one drive. |
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With RAID level-1E, if one of the physical drives fails, the controller switches read and write requests to the remaining functional drives in the RAID level-1E pool.
RAID level-1E offers the following advantages and disadvantages:
Advantages | Disadvantages |
---|---|
|
Allows only 50% of the physical drive storage capacity to be used |
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