💾 Storage and LVM

Understanding how Linux stores, organizes and protects data.

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Table of Contents

1. Why Storage Matters
2. Physical Disks
3. Disk Layout
4. Partitions
5. Why Use Partitions?
6. Filesystems
7. Mount Points
8. The Linux Filesystem Tree
9. Common Mount Points
10. What Happens During Boot?
11. LVM Introduction
12. Why LVM Exists
13. Physical Volumes
14. Volume Groups
15. Logical Volumes
16. LVM Workflow
17. LVM Advantages
18. Encryption
19. Why Encrypt Data?
20. LUKS Concepts
21. Storage Commands
22. Mental Model

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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.

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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.

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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.

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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.

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5️⃣ Why Use Partitions?

Partitions provide:

✅ Organization

✅ Isolation

✅ Easier management

✅ Better security

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Example:

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

If one partition fills up, the others remain unaffected.

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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.

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Common filesystems:

• ext4
• XFS
• Btrfs

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Think of a filesystem as:

The filing system of a library

It determines where everything is stored.

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7️⃣ Mount Points

Linux does not assign drive letters like Windows.

Instead, storage is attached to directories.

This process is called:

Mounting

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Example:

Storage Device
      ↓
Mount Point
      ↓
/home

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8️⃣ The Linux Filesystem Tree

Linux has a single directory tree.

Everything starts at:

/

called:

Root Directory

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Example:

/
├── home
├── var
├── boot
└── etc

Additional storage is attached somewhere inside this tree.

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9️⃣ Common Mount Points

/home

User files.

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/var

Logs and changing data.

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/boot

Boot-related files.

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/

Root filesystem.

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Example:

Disk A
   ↓
/

Disk B
   ↓
/home

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🔟 What Happens During Boot?

When Linux starts:

1. Detect storage
2. Load filesystems
3. Mount partitions
4. Make data available

Only after mounting can files be accessed.

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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.

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1️⃣2️⃣ Why LVM Exists

Traditional partitions are rigid.

Example:

Partition = 20 GB

If it becomes full, resizing may be difficult.

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LVM introduces flexibility.

Instead of thinking about fixed partitions:

Think about storage pools

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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.

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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.

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This is one of LVM's biggest advantages.

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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.

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1️⃣6️⃣ LVM Workflow

The easiest way to remember LVM:

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

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Or visually:

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

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1️⃣7️⃣ LVM Advantages

Benefits include:

✅ Easier resizing

✅ Flexible storage

✅ Better management

✅ Storage pooling

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Example:

Traditional partition:

20 GB

Needs more space?

Often difficult.

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LVM:

20 GB
      ↓
40 GB

Usually much easier to expand.

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1️⃣8️⃣ Encryption

Encryption protects stored data.

Without the correct key:

Data remains unreadable

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Encryption converts:

Readable Data

into:

Protected Data

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1️⃣9️⃣ Why Encrypt Data?

Imagine someone steals a hard drive.

Without encryption:

Files may be readable

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With encryption:

Files appear meaningless

without the correct credentials.

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Benefits:

✅ Privacy

✅ Security

✅ Theft protection

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2️⃣0️⃣ LUKS Concepts

LUKS is commonly used for disk encryption on Linux.

Think of it as:

A lock protecting storage

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Example:

Disk
   ↓
LUKS
   ↓
Filesystem

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

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2️⃣1️⃣ Storage Commands

Display disks:

lsblk

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Display mounted filesystems:

df -h

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Display filesystem usage:

du -sh folder

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Display partition information:

fdisk -l

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Display mount information:

mount

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Display LVM information:

pvs
vgs
lvs

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These commands help administrators understand storage layout.

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2️⃣2️⃣ Mental Model

Imagine a shopping center.

The disk is:

The entire building

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Partitions are:

Individual stores

---

Filesystems are:

The organization system
inside each store

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LVM is:

A manager capable of
expanding or shrinking stores
when needed

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Encryption is:

A lock on the building

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Final Mental Image

Disk
  ↓
Partition
  ↓
Filesystem
  ↓
Mount Point

Traditional storage.

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Disk
  ↓
PV
  ↓
VG
  ↓
LV
  ↓
Filesystem

LVM storage.

This extra layer is what gives LVM its flexibility.