Originally posted by gm4life Forgive me. I'm an IT guy with a background in infrastructure. I need to either correct your terms or inform you of a glaring hole in your protection.
RAID 0 offers ZERO protection. It is a method of extending across disks at the hardware level across more than one drive via striping. In RAID 0 the loss of any of the drives renders all the data on all the drives useless.
RAID 1 is more commonly used with two drive cabinets like that. In this version of RAID, you have half the total capacity (4TB for a pair of 4TB drives) and each time the drives are written to both drives write the same data before the write is considered complete.
Other forms of RAID exist but with only two drives the only other commonly used configurations are independant drives or JBOD neither of which offer any data protection.
So I hope you are using RAID 1 and you just didn't state things correctly - because if you are using RAID 0 - you have a major risk to your data - more than if you used each drive as a separate 4TB volume since either disk failing will take the entire 8TB down.
The way you describe it sounds like RAID 1. 4TB total capacity - with two fully redundant drives holding identical copies of the same data. In the event of failure the dead drive should be replaced and the cabinet should mirror the data over if it includes a hardware raid controller. If not then your OS will accomplish this.
---------- Post added 01-17-17 at 01:03 AM ----------
Oh and the WD Duo is reasonably well respected and a rational way to implement RAID 1 mirrored drives. It is supposed to have a hardware raid card which is a good idea since it offloads a lot of CPU tasks to the controller rather than the main CPU.