Hello,
The WD My Cloud device supports the following formats:
FAT32
NTFS (read and write capability)
HFS+J
Linux Ext2, Ext3/Ext4
XFS
Check page #116 of the WD My Cloud User’s manual for more information.
http://www.wdc.com/wdproducts/library/UM/ENG/4779-705103.pdf