💾 Storage and LVM¶

Understanding how Linux stores, organizes and protects data.

Table of Contents¶

Why Storage Matters
Physical Disks
Disk Layout
Partitions
Why Use Partitions?
Filesystems
Mount Points
The Linux Filesystem Tree
Common Mount Points
What Happens During Boot?
LVM Introduction
Why LVM Exists
Physical Volumes
Volume Groups
Logical Volumes
LVM Workflow
LVM Advantages
Encryption
Why Encrypt Data?
LUKS Concepts
Storage Commands
Mental Model

1️⃣ Why Storage Matters¶

Every operating system needs a place to store:

files
applications
configuration
logs
user data

Without storage, all information would disappear when the computer shuts down.

2️⃣ Physical Disks¶

Storage begins with a physical device.

Examples:

HDD (Hard Disk Drive)
SSD (Solid State Drive)
NVMe SSD

Linux sees these devices as storage resources that can be organized and divided.

3️⃣ Disk Layout¶

Think of a disk as a completely empty piece of land.

Entire Disk
┌───────────────────┐
│                   │
│    Empty Space    │
│                   │
└───────────────────┘

Before it can be used efficiently, it is usually divided into sections.

4️⃣ Partitions¶

A partition is a logical division of a disk.

Example:

Disk
├── Partition 1
├── Partition 2
└── Partition 3

Each partition behaves almost like an independent storage area.

5️⃣ Why Use Partitions?¶

Partitions provide:

✅ Organization

✅ Isolation

✅ Easier management

✅ Better security

Example:

Partition 1 → System
Partition 2 → User Files
Partition 3 → Logs

If one partition fills up, the others remain unaffected.

6️⃣ Filesystems¶

A filesystem defines how data is stored and organized.

Without a filesystem:

Disk = Raw Storage

Linux would not know how to manage files.

Common filesystems:

ext4
XFS
Btrfs

Think of a filesystem as:

The filing system of a library

It determines where everything is stored.

7️⃣ Mount Points¶

Linux does not assign drive letters like Windows.

Instead, storage is attached to directories.

This process is called:

Mounting

Example:

Storage Device
      ↓
Mount Point
      ↓
/home

8️⃣ The Linux Filesystem Tree¶

Linux has a single directory tree.

Everything starts at:

called:

Root Directory

Example:

/
├── home
├── var
├── boot
└── etc

Additional storage is attached somewhere inside this tree.

9️⃣ Common Mount Points¶

/home¶

User files.

/var¶

Logs and changing data.

/boot¶

Boot-related files.

/¶

Root filesystem.

Example:

Disk A
   ↓
/

Disk B
   ↓
/home

🔟 What Happens During Boot?¶

When Linux starts:

Detect storage
Load filesystems
Mount partitions
Make data available

Only after mounting can files be accessed.

1️⃣1️⃣ LVM Introduction¶

LVM means:

Logical Volume Manager

This is one of the most important Born2beroot concepts.

Many students struggle with it because it adds an extra layer between the disk and the filesystem.

1️⃣2️⃣ Why LVM Exists¶

Traditional partitions are rigid.

Example:

Partition = 20 GB

If it becomes full, resizing may be difficult.

LVM introduces flexibility.

Instead of thinking about fixed partitions:

Think about storage pools

1️⃣3️⃣ Physical Volumes¶

A Physical Volume (PV) is storage managed by LVM.

Example:

Disk
   ↓
Physical Volume

Think of a PV as raw storage that LVM can use.

1️⃣4️⃣ Volume Groups¶

A Volume Group (VG) combines storage.

Example:

PV1 = 100 GB
PV2 = 100 GB

VG = 200 GB

Multiple disks can be combined into a single storage pool.

This is one of LVM's biggest advantages.

1️⃣5️⃣ Logical Volumes¶

Logical Volumes (LVs) are created from the Volume Group.

Example:

Volume Group
     ↓
 ├── LV Home
 ├── LV Root
 └── LV Logs

To Linux, these behave similarly to partitions.

1️⃣6️⃣ LVM Workflow¶

The easiest way to remember LVM:

Disk
  ↓
Physical Volume (PV)
  ↓
Volume Group (VG)
  ↓
Logical Volume (LV)
  ↓
Filesystem

Or visually:

Disk
 │
 ▼
PV
 │
 ▼
VG
 │
 ▼
LV
 │
 ▼
ext4

1️⃣7️⃣ LVM Advantages¶

Benefits include:

✅ Easier resizing

✅ Flexible storage

✅ Better management

✅ Storage pooling

Example:

Traditional partition:

20 GB

Needs more space?

Often difficult.

LVM:

20 GB
      ↓
40 GB

Usually much easier to expand.

1️⃣8️⃣ Encryption¶

Encryption protects stored data.

Without the correct key:

Data remains unreadable

Encryption converts:

Readable Data

into:

Protected Data

1️⃣9️⃣ Why Encrypt Data?¶

Imagine someone steals a hard drive.

Without encryption:

Files may be readable

With encryption:

Files appear meaningless

without the correct credentials.

Benefits:

✅ Privacy

✅ Security

✅ Theft protection

2️⃣0️⃣ LUKS Concepts¶

LUKS is commonly used for disk encryption on Linux.

Think of it as:

A lock protecting storage

Example:

Disk
   ↓
LUKS
   ↓
Filesystem

Before data can be accessed, the lock must be opened.

2️⃣1️⃣ Storage Commands¶

Display disks:

lsblk

Display mounted filesystems:

df -h

Display filesystem usage:

du -sh folder

Display partition information:

fdisk -l

Display mount information:

mount

Display LVM information:

pvs
vgs
lvs

These commands help administrators understand storage layout.

2️⃣2️⃣ Mental Model¶

Imagine a shopping center.

The disk is:

The entire building

Partitions are:

Individual stores

Filesystems are:

The organization system
inside each store

LVM is:

A manager capable of
expanding or shrinking stores
when needed

Encryption is:

A lock on the building

Final Mental Image

Disk
  ↓
Partition
  ↓
Filesystem
  ↓
Mount Point

Traditional storage.

Disk
  ↓
PV
  ↓
VG
  ↓
LV
  ↓
Filesystem

LVM storage.

This extra layer is what gives LVM its flexibility.