sudo mkfs.ext4 -L 'Alt_OS' /dev/sdc
mke2fs 1.42.5 (29-Jul-2012)
/dev/sdc is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=Alt_OS
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
256000 inodes, 1024000 blocks
51200 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1048576000
32 block groups
32768 blocks per group, 32768 fragments per group
8000 inodes per group
Superblock backups stored on blocks: 
 32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done