WD external USB HD not detected/mounted by my NAS WDmycloudEX4

My Cloud OS 3 Personal & Network Attached Storage My Cloud EX4
3

It should support ext4, too, being a linux system.

I got it working a couple of days ago!

With my Ubuntu linux box using gparted I delete the original partition and create two ones of 2 TB each and I formatted both with EXT4 (not sure it was needed)

Then I attached the USB disk on the NAS. Using dmesg I got what device (/dev/sdX) the NAS was unable to mount.

Then I reformatted the partitions:

root@WDMyCloudEX4 root >  mkfs.ext4 /dev/sdc1
root@WDMyCloudEX4 root > mkfs.ext4 /dev/sdc2

Finally I found the two new USB devices (I don’t remember if I reboot the NAS or just waited):

root@WDMyCloudEX4 root > ls /mnt/USB/
USB2_c1  USB2_c2

Now I’m following this guide [GUIDE] How to Make Persistent System Changes (crontab, etc) to use rsync to backup my NAS shares.