while i am entering in my server to format my custom amazon volume it shows like this

ubuntu@ip-10-204-43-33:~$ sudo mkfs -t ext4 /dev/sdn
mke2fs 1.41.11 (14-Mar-2010)
/dev/sdn is entire device, not just one partition!
Proceed anyway? (y,n)

it shows like /dev/sdn is entire partiotion so what s wrong with this? what i have to do?
Is it cause any problem?

as well as look down for my fdisk -l and give your suggestion plz

Disk /dev/sdn: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdn doesn't contain a valid partition table