Hi Puerto,
Would that be
this one, or
this one?
The first one (more expensive) only has 1 feedback comment at NewEgg, which is positive. But the second one (less expensive) has seven comments, many of which describe serious problems.
Given also that WD Black HD's are generally excellent drives, IME and IMO, it sure sounds like the Cavalry unit may be the problem.
Also, my philosophy is that RAID 1 should not be counted on as a backup solution, or at least as the only backup solution, because it is conceivable that a failure of the RAID controller hardware, or the power supply, or the operating system, or a virus infection, could simultaneously corrupt or destroy both drives in the array. Thankfully you've recognized that possibility by keeping a separate single HD as an additional backup.
So I would think that the best approach to resolving these frustrating experiences would be to forget about RAID and simply store your music on at least two non-RAID external hard drives, preferably Western Digitals IMO. And preferably drives that are fully enclosed, as opposed to being dock-mounted, which may help with respect to the humidity situation.
Regards,
-- Al