Lesson 1: The Architect (Disks & Mounts)

A server's storage is not just "one big hard drive." It's a collection of partitions, filesystems, and mount points — all carefully organized like the floors and rooms of a building.

The Linux Filesystem Hierarchy

Everything in Linux starts at / (root). Unlike Windows (C:, D:), Linux mounts all disks into a single unified tree:

/
├── /home        → User files
├── /var         → Variable data (logs, databases)
├── /etc         → Configuration files
├── /tmp         → Temporary files (cleared on reboot)
├── /opt         → Optional/third-party software
├── /mnt         → Temporary mount point
└── /dev         → Device files (your disks live here)

Block Devices: `lsblk`

lsblk lists all storage devices and their partitions:

NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0   50G  0 disk
├─sda1   8:1    0   49G  0 part /
└─sda2   8:2    0    1G  0 part [SWAP]
sdb      8:16   0  100G  0 disk
└─sdb1   8:17   0  100G  0 part /data

sda — First disk.
sda1 — First partition on the first disk.
MOUNTPOINT — Where it's accessible in the filesystem.

Mounting & Unmounting

Mounting = connecting a disk partition to a directory.

mount /dev/sdb1 /mnt/data    # Make the disk accessible at /mnt/data
umount /mnt/data              # Disconnect it safely

The `/etc/fstab` File

This file tells Linux which disks to automatically mount at boot. Each line specifies:

device    mount_point    filesystem    options    dump    pass
/dev/sda1    /           ext4         defaults    0       1
/dev/sdb1    /data       ext4         defaults    0       2

If you add a new disk and want it to persist across reboots, you must add it to /etc/fstab.

booting...

Mission Objective

Survey the storage architecture:

Map the terrain: Run lsblk to see all disks and partitions.
Check connections: Run mount | head -10 to see what's currently mounted.
Read the blueprint: Run cat /etc/fstab to see the permanent mount configuration.

Real-World Note

In cloud environments (AWS EBS, GCP Persistent Disks), you frequently attach and mount new volumes. Forgetting to update /etc/fstab means your data volume won't reconnect after a reboot!