The 4TB WD My Cloud does not come with SNMP.
However you may be able to get the device OS to install SNMP using SSH. Doing so will probably void the warranty on the WD My Cloud since WD indicates using SSH can void the warranty. SSH can be enabled via the WD My Cloud user interface (Settings → Network → Network Services → SSH)
You can try the steps at the following link as a starting point, even though its for the My Book Live Duo, but you proceed at your own risk! Any time you muck around with SSH you run the risk of potentiality bricking the unit.
http://community.wd.com/t5/My-Book-Live-Duo/Is-the-My-Book-Duo-SNMP-capable/td-p/679853
