Acceptable performance. Unfortunately, no power button.

I was really curious if the Thunderbolt port delivers what it promises. Thunderbolt advertises with transfer rates of 10 Gb / s. Only what's the point if the hardware on the opposite side does not participate in this transmission rates me.

In the present case, I rate the MyBook Thunderbolt Duo 4TB Western Digital.

The fine print on the packaging can be found in the English language, this plate is a transfer rate of> 225 MB / s makes. OK, that's different than 10 Gb / s (1.25GB / s). Oh well ...

The second question that came to me is WD can keep this promise reprinted? The answer is YES! At least in RAID 0 mode. Reflects the disk the data in RAID 1 are significantly less. However, it was clear by experience with network drives.

If the disk exploits nor the full potential which is the Thunderbolt port Apple able to afford to the transmission rates are still higher than in non-Thunderbolt hard drives, especially and made me pleasantly surprised, quite constant data rates 170-200 MB / s. Great! Was it for Thunderbolt? I think so!

In RAID 1 I come to scarce 90 100 MB / s. That's perfectly fine, but not mega fast. If you would like to address the hard disks separately, you can also switch on the JBOD mode. However, I use RAID 1, because the data is stored on secure. Incidentally, I have no problems with the integration of the plates in Time Machine.

The active data transfer is indicated by a small, relatively unobtrusive LED on the front. Good!

The housing can be opened easily and without tools, so you can replace the hard disk easily. WD Caviar Green are built with 64 MB cache. A speed is not specified. The WD Green hard drives operate on the IntelliPower process. Lt means. WD balance between rotation speed, transfer rate and caching algorithms.

The noise, yes you can hear the hard drives, is my feeling after a pleasantly quiet.
A WD Caviar Black would be faster, but certainly also been louder.

Unfortunately, the hard disk is missing a switch, so I always pull the plug. The sleep mode, I know it from my WD Live network drives, I do not trust. Although the disks rotate slowly, they do it. And that is determined in the long run not particularly conducive as far as the life cycle.

The housing is as always with WD from "high quality" plastic, here in MacBook outfit. However, the processing is absolutely OK.

Ideally it would have been if the plate next to the Thunderbolt port at least one albeit USB 2.0 port would have had yet, so I could at least access directly with my Windows PC (second computer) on the plate. Too bad, but the plate happens to be declared Thunderbolt hard drive. In other connectors, the panel would probably have become significantly more expensive.

Incidentally, a Thunderbolt cable not included. At least WD writes the highly visible right on the front of the packaging. The cable suggests almost 50 euros. Since there are few Thunderbolt hard drives on the market, I find the price / performance ratio absolutely OK. After all costs alone 2 x 2 TB at the present time nearly 200-220 Euro.

In summary:
+ Acceptable transfer rates (compared to USB and Co.)
+ Ordinary processing
+ Noise (quiet)
+ RAID 0, 1 and JBOD
+ Time Machine compatible
+ Acceptable price / performance ratio
+ 3 years warranty

+ - (Neutral) No further connection option, touted at least as pure Thunderbolt hard drive and therefore unfair to evaluate it negatively.

- Plastic housing
- No on / off switch
- Included No Thunderboltkabel

If I can aufwiege the positive and negative to give 3.5 out of 5 stars. But is not, so I round in favor WD.

A recommendation can I say!