Hi,
I have a WD Elements 500GB which runs under OS X Maverick 10.9.1. The disk ejects randomly which causes aborted write operations and making it quite useless as a backup disk. I ran the disk in the following configurations and always got the eject behaviour. Only the time is hard to predict, sometimes after a minute, sometimes after an hour. My guess is that it depends on the load.
Tested configurations:
ExFat on a Mac mini (2011)
HFS on a Mac mini (2011)
ExFat on a MacBook late 2008 unibody
HFS on a MacBook late 2008 unibody
Edit:
Even tested as an external disk on a Time Capsule. The WD disk also suddenly ejects.
Different cables (the one provided with the disk, another USB3 cable and a USB2 cable) were also tested in all configurations.
Any suggestions?