There are several scenarios for what happens when a disk fails.

If any disk in the pool fails, the data can be reconstructed using this additional information.

Yet one thing is certain: some day, whether through human error or mechanical failure, every hard disk will fail.

Hard disks fail, although not as often as they used to.

Stopping data loss, when one or more disks of the array fail.

If this is not repaired before a disk or block fails, data loss may occur.

In that array, one disk can fail without data loss.

In practice, there is a chance that a second disk will also fail before the first has been recovered.

Even after the disk failed, the data on the array can still be used.

The answer is clear enough, though the disk itself fails to provide appropriate lessons for how such potential is to be developed.