If this configuration is a RAID array, what happens when you plug in a different variety of disks?
The details aren't posted but it is highly likely that each of these enclosures present to the Mac as a single 6TB disk ( are in RAID-0 mode). Then for the demo they use Disk Utility to create a software RAID on top of that to get RAID spanning ( stripe width 4 over 6TB disks ) across the enclosures.
WD could have changed/updated the "Drive Manager" software to do the spanning across boxes but it would been simplier and cheaper to just let Disk Utility do it.
In other words, each of these disks present independently. So if you add another disk, it too will present as independent. There is software on the mac gluing those disks together into one big virtual volume.
I seriously doubt the RAID controller in one of those boxes is accessing drives in other boxes to present as a larger volume straight from that single box.
A more reasonable demo would have been a 12TB RAID 10 set up. It is still a relatively huge amount of storage and has more resiliency. However, the demo is geared to peg that "read" dial in the red zone.
After setup, does that mean you can now only use the 4 drives together?
Permanently? No. If you reformat them you can use them for other purposes. If you mean can you just remove disks from a RAID-0 set up and used regularly. No. But that isn't unique to these specific enclosures.
Even if they had been set up as a RAID-SPAN configuration you can generally rip drives out of the config and just use as a regularly volume. There are parts of the file system missing.
----------
*sigh* where the heck are the Thunderbolt to eSATA adapters!? I've already GOT a bloomin' RAID array...
You mean like this story posted to MacRumors several weeks ago?
https://forums.macrumors.com/threads/1305703/
http://www.cnet.com/8301-17914_1-57354003-89/lacie-turns-thunderbolt-budget-friendly-with-esata-hub/
----------
My personal opinion is that USB 3 is going to kill thunderbolt off unless prices for TB start dropping to a reasonable price. Ive already got a FW800/USB3 enclosure just waiting for the ivy bridge macs to come out, in the meantime its running on FW800.
USB 3.0 didn't kill off the FW800 on your enclosure. It is unlikely to kill off Thunderbolt. USB 3.0 and TB are aimed at overlapping markets. Most of the overlap is outside the intersection between the two. It isn't going to "kill off" TB. Neither is TB going to "kill off" USB 3.0. They both are going to be on systems.
USB 3.0 peripherals will probably have a lower average selling price and be much more numerous. TB peripherals will have a higher average selling price and be "large enough to be a viable market".
eSATA and FW are at much better threat by the combination of those two. USB 3.0 from "below" and TB from "above" to shrink their share of the market over time. Those two largerly fit inside that intersection.
TB will also eat into the 4x (and smaller) discrete PCI-e card market. [not a big deal for those vendors since the guts of the cards can just be repackaged as a higher priced TB devices. ]
