lsblk

The lsblk command is used to list all the storage devices (block devices) connected to the system. It shows the device name as well as any partitions that may have been created on the device. In addition, it shows the capacity (size) of the device, the device type, and the mount point if it has been attached to the Linux file system.

[alice@localhost ~]$ lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda           8:0    0   20G  0 disk 
├─sda1        8:1    0    1G  0 part /boot
└─sda2        8:2    0   19G  0 part 
  ├─cl-root 253:0    0   17G  0 lvm  /
  └─cl-swap 253:1    0    2G  0 lvm  [SWAP]
sdb           8:16   0    8G  0 disk 
sr0          11:0    1  1.7G  0 rom

The example output shows two disks attached to the Linux system (sda and sdb). The first disk, sda, has two partitions allocated (sda1 and sda2) which contain the root file system (/) and the initial boot file system (/boot). The second disk, sdb, has no partitions allocated and is not currently mounted as part of the Linux file system.

Notice that the second partition (sda2) is further divided into cl-root andcl-swap using LVM (Logical Volume Manager) and that these LVM devices are in fact the devices that are mounted. LVM is a more powerful and flexible mechanism for managing storage space on block devices, but it is beyond the scope of this guide.