lsblk

lsblk list all block level devices available on your system.

Example

root@ok:~# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  100G  0 disk 
├─sda1   8:1    0   98G  0 part /
├─sda2   8:2    0    1K  0 part 
└─sda5   8:5    0    2G  0 part [SWAP]
sdb      8:16   0  700G  0 disk 
└─sdb1   8:17   0  700G  0 part /backup
sr0     11:0    1  655M  0 rom  
loop0    7:0    0 36.4M  1 loop /snap/heroku/1513
loop1    7:1    0 83.8M  1 loop /snap/core/3748
loop2    7:2    0   16M  1 loop /snap/heroku/1527
root@ok:~# 

See fs