parted

parted -a opt /dev/md0
(parted) u MiB
(parted) rm 1
(parted) mkpart primary 1 100%

or an alternate dirty method would simply go like this

(parted) mkpart primary ext4 1 -1

Partition a 4tb external drive:
parted -a opt /dev/sdc
mklabel gpt
unit TB 
mkpart primary 0.00TB 4.00TB
align-check optimal 1 (check if the partition is aligned)
quit
mkfs.ext4 /dev/sdc1

You  might want to reduce the reserved for defragmentation to 1% with such a large drive.

tune2fs -m 1 /dev/sdc1