qm-disk-import
Import a disk image to a virtual machine as an unused disk.
TLDR
Import a VMDK/qcow2/raw disk image using a specific storage name
$ qm importdisk [vm_id] [path/to/disk] [storage_name] --format [qcow2|raw|vmdk]
Import a VMDK/qcow2/raw disk image using a specific storage name