Attaching another drive while doing a RAID change on a Mac can reformat the second drive
Problem:
Attaching another drive while doing a RAID change can reformat the second drive.
Cause:
If the second drive is assigned the same unix device name that was assigned to the RAID device before it was dismounted from the system, the second drive will be reformatted.
Solution:
External drives should not be removed or attached during a RAID change operation.