WD My Book Duo iMac

I use the My Book Duo on an iMac with USB 3.0 interface and Yosemite.
After first plugging in the drive does not appear only once in the Finder. It must be installed for the Mac first, the WD software. This was quick and easy with me.
Then the drive will appear and should now be re-formartiert for the Mac because it's preformatted for Windows. This, too, was quite fast.
Then you should decide whether to the
Would at maximum capacity or maximum security (ie half the capacity, mirroring the contents) use double hard drive (RAID configuration). This, too, went smoothly.
In operation, the dual hard drive is very quiet, especially compared to my older USB disk from which I backed up.
Now, if the hard drives still quite long work fine, I can only recommend to buy.