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