Block Devices and Partitions

Introduction

Imagine looking at an office building blueprint.

The Building: Disk Drive (Physical Storage).
The Rooms: Partitions (Logical sections).
Room Name: Mount Point (Access path like /home).

In this lab, you will use lsblk to visualize this blueprint.

This layered view is important because Linux storage is built in stages. A physical or virtual device may contain partitions, those partitions may contain filesystems, and those filesystems may then be mounted into the main directory tree.

List All Block Devices (lsblk)

View the storage blueprint with lsblk (List Block Devices).

lsblk

Output:

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0    7:0    0     4K  1 loop /snap/bare/5
...
vda    252:0    0    40G  0 disk
├─vda1 252:1    0     1M  0 part
└─vda3 252:3    0  39.8G  0 part /

Understanding the Tree:

NAME: vda is the disk. vda1 is a partition. loopX are virtual devices (ignore for now).
SIZE: Capacity (e.g., 40G).
TYPE: disk, part (partition), or loop.
MOUNTPOINTS: Where data is accessed (e.g., / is root).

This is why lsblk is so helpful for beginners. It shows relationships, not just names, helping you see which storage objects sit on top of which others.

Save the blueprint:

lsblk > devices.txt

Filter Physical Disks (lsblk -d)

Too much detail? Show only disks, hide partitions.

Use -d (device):

lsblk -d

Output:

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0    7:0    0     4K  1 loop ...
vda    252:0    0    40G  0 disk

Partitions (vda1, vda2) are gone.

This lists only top-level devices.

Filtering between full tree views and top-level device views is useful because storage troubleshooting often shifts between "Which disks exist?" and "How is this disk divided?"

Save the list:

lsblk -d > disks.txt

Check Filesystems (lsblk -f)

What format are the partitions?

Use -f (filesystem) to see the Type and UUID.

lsblk -f

Output:

NAME   FSTYPE   FSVER LABEL UUID                                 ...
vda
├─vda2 vfat     FAT32       8E24-7BB2                            ...
└─vda3 ext4     1.0         7504cd7e-f775...                     ...

FSTYPE: e.g., ext4 (Linux), vfat (EFI).
UUID: Unique ID (Fingerprint), crucial for auto-mounting.

UUIDs matter because device names can sometimes change depending on boot order or attached hardware. A UUID gives you a more stable identifier for configuration.

Save details:

lsblk -f > filesystems.txt

Check Exact Size (lsblk -b)

Need exact bytes for scripts?

Use -b (bytes) to remove units like "G" or "M".

Raw byte output is especially useful in scripts and automation, where exact numbers matter more than human readability.

lsblk -b

Output:

NAME   ... SIZE ...
vda    ... 42949672960 ...

Save raw data:

lsblk -b > sizes.txt

Summary

In this lab, you learned to read the "blueprint" of your Linux storage using the lsblk command.

lsblk: Showed you the tree structure of Disks (Buildings) and Partitions (Rooms), including virtual loop devices.
lsblk -d: Filtered the view to show only the top-level devices (ignoring partitions).
lsblk -f: Revealed the "interior decoration" (Filesystem Type) and unique ID (UUID).
lsblk -b: Gave you the precise size measurements in bytes.

Understanding these storage devices is the first step to managing them—whether you are adding a new hard drive, resizing a partition, or just checking why the server is full.