I’ve seen four My Cloud drives opened and all of them had Red drives. Others here report Red drives in their My Cloud’s as well.
https://community.wd.com/t/shock-horror-western-digital-my-cloud-devices-use-wd-green-drives/95399
MyCloud is based on Western Digital’s WD Red hard drives specifically designed for regular NAS use and features a new dual-core processor.
http://arstechnica.com/gadgets/2014/01/western-digital-my-cloud-review-the-150-personal-cloud/
The My Cloud line comes with Western Digital’s Red drives, which are designed to be used in consumer network-attached storage (NAS) systems.
