# Understanding when RAID level-x0 logical drives change state

Start with four physical drives.

Use two physical drives to create array A and two physical drives to create array B.

Use arrays A and B to create spanned array 1. As part of a spanned array, arrays A and B are now called "subarrays."

A sub-logical drive is created in array A and another sub-logical drive is created in array B.

Then, create a logical drive in spanned array 1.

If the sub-logical drive in subarray A is in the okay state and the sub-logical drive in subarray B is in the okay state, then the logical drive in spanned array 1 is in the okay state.

If a physical drive fails in subarray A, then the sub-logical drive in subarray A changes to the critical state. Subarray B is still in the okay state. The logical drive in spanned array 1 changes to the critical state.

If the second physical drive fails in subarray A, then the sub-logical drive in subarray A changes to the offline state. Subarray B remains in the okay state. The logical drive in spanned array 1 changes to the offline state.

If the sub-logical drive in subarray A is in the critical state and a physical drive fails in subarray B, then the sub-logical drive in subarray B changes to the critical state. With both sub-logical drives in the critical state, the logical drive in spanned array 1 remains in the critical state.

## More information

- Understanding creating spanned arrays
- Creating spanned arrays in the wizard
- Understanding RAID level-x0
- Physical drive capacity and unusable capacity
- Understanding creating basic arrays

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