Never use identical drives in a mirror. The same model is Ok but the exact same age is not. I always try to "engineer" a controlled failure by using one old and one new drive.
But none of this can defeat human error.
But none of this can defeat human error.
After a couple of years, I replace one drive with a new one. Keep the removed drive to use for offline data backup.
Run until failure or 5 years, which ever comes first. Then replace the oldest or failed drive with a new one. Wash, rinse and repeat.