I recently bought another block of storage from my provider and following their guide, I rearranged my accounts to it:
sudo mkfs.ext4 /dev/vdbsudo mkdir /mnt/vol-us-1sudo mount -t ext4 /dev/vdb /mnt/vol-us-1bin/bash -c "if [ $(cat /etc/fstab | grep -i /dev/vdb | awk '{print $1}')!="/dev/vdb" ]; then sudo bash -c 'echo \/dev/vdb /mnt/vol-us-1 ext4 defaults,nofail,discard,noatime 1 2\ >> /etc/fstab';fi"
This worked initially, but then I ran through an upgrade for WHM and I lost my settings, and the storage block seemed to have been wiped. I was able to recover from a backup, but not entirely.
I can see in my Disk Usage report that the mount exists: 
But then trying to move my account, WHM doesn't let me do it:
