I recently came across a rather splendid command that shows your drives and their percentage of free space. And it is -
df -hP |column -t |tee >( head -n1 > /dev/stderr ) |grep % |sort -k5nr
and in my case it shows this -
Filesystem Size Used Avail Use% Mounted on /dev/sdd1 2.7T 2.0T 579G 78% /media/boudiccas/back1 /dev/sda1 287G 147G 126G 54% / /dev/sde1 2.7T 1.2T 1.5T 46% /media/boudiccas/back3 /dev/sdc1 917G 298G 573G 35% /media/boudiccas/back4 /dev/sdb1 1.8T 322G 1.4T 19% /media/boudiccas/back2 tmpfs 354M 40M 315M 12% /run tmpfs 2.1G 80K 2.1G 1% /run/shm Filesystem Size Used Avail Use% Mounted on none 4.0K 0 4.0K 0% /sys/fs/cgroup tmpfs 5.0M 0 5.0M 0% /run/lock udev 10M 0 10M 0% /dev
As you can see it ranks your drives by their usage, which is rather nice.