Am satisfied with the connected hard drive, the Mac Time Machine is activated and it worked flawlessly. Let's see if in the long term the WD device is well worth the price .. Only 4 stars because I consider unnecessary additional surcharge for Mac! Addendum: Did the device now for several months and runs without problems (even on USB 2.0 / MacBook Pro). Even with Update Yosemite it works without problems. Plugging Update runs automatically - what more could you want!