Storage Management & Partitioning

Disk Architecture in Linux

Linux represents disks as device files in /dev/:

Device	Type
`/dev/sda`	First SATA/SCSI disk
`/dev/sdb`	Second SATA/SCSI disk
`/dev/nvme0n1`	First NVMe disk
`/dev/sda1`	First partition on sda

Listing Disks and Partitions

lsblk — Block Devices

lsblk

Output:

NAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
nvme0n1      259:1    0    8G  0 disk
├─nvme0n1p1  259:3    0  7.9G  0 part /
├─nvme0n1p14 259:4    0    4M  0 part
└─nvme0n1p15 259:5    0  106M  0 part /boot/efi
nvme1n1      259:0    0    5G  0 disk

fdisk — Detailed Disk Info

sudo fdisk -l

File System Info

# Show file system types
sudo lsblk -f
 
# Check specific partition
sudo blkid /dev/nvme0n1p1

File Systems

A file system organizes data on a partition. You must format a partition before using it.

File System	Description	Best For
ext4	Standard Linux FS, journaling	General purpose
xfs	High-performance, scalable	Large files, databases
btrfs	Copy-on-write, snapshots	Advanced features
vfat	FAT32, cross-platform	Boot partitions, USB

Creating Partitions with fdisk

# Open fdisk on a disk
sudo fdisk /dev/nvme1n1

Interactive commands:

Key	Action
`n`	Create new partition
`p`	Print partition table
`d`	Delete a partition
`t`	Change partition type
`w`	Write changes and exit
`q`	Quit without saving

Step-by-Step: Create a 2GB Partition

sudo fdisk /dev/nvme1n1

Command: n          # New partition
Select: p           # Primary
Partition number: 1 # First partition
First sector: Enter # Accept default
Last sector: +2G    # 2GB size
Command: w          # Write and exit

Verify:

lsblk

Formatting Partitions

Create a file system on the new partition:

# Format as ext4
sudo mkfs -t ext4 /dev/nvme1n1p1
 
# Format as xfs
sudo mkfs -t xfs /dev/nvme1n1p1
 
# Add a label
sudo e2label /dev/nvme1n1p1 "DATA"

Mount Points

A mount point is a directory where a partition's contents become accessible.

Mounting a Partition

# Create mount point
sudo mkdir -p /data
 
# Mount the partition
sudo mount /dev/nvme1n1p1 /data
 
# Verify
df -hT | grep data

Unmounting

sudo umount /data
# or
sudo umount /dev/nvme1n1p1

⚠️

You cannot unmount a partition if any process is using files on it. Use lsof /data to find which processes are accessing it.

Checking Mounted File Systems

# All mounted file systems
df -hT
 
# Specific mount
mount | grep nvme1n1

Persistent Mounts with /etc/fstab

Mounts created with mount are lost on reboot. Make them persistent:

# View current fstab
cat /etc/fstab

Example fstab entry:

# <device>              <mount>    <type>  <options>       <dump> <fsck>
UUID=b78a0d9e-5657...   /data      ext4    defaults        0      2
LABEL=DATA              /data      ext4    defaults        0      2

Columns Explained

Column	Purpose
Device	UUID, LABEL, or device path
Mount point	Directory to mount on
Type	File system type (ext4, xfs)
Options	Mount options (defaults, ro, noexec)
Dump	Backup flag (0 = no)
Fsck	Check order (0 = skip, 1 = root, 2 = others)

Adding a Persistent Mount

# Get the UUID
sudo blkid /dev/nvme1n1p1
 
# Edit fstab
sudo nano /etc/fstab
 
# Add line:
UUID=your-uuid-here /data ext4 defaults 0 2
 
# Test without rebooting
sudo mount -a

💡

Always use UUID in fstab instead of device names like /dev/sdb1. Device names can change between reboots, but UUIDs are permanent.

Deleting Partitions

# Unmount first
sudo umount /dev/nvme1n1p1
 
# Open fdisk
sudo fdisk /dev/nvme1n1
 
# Delete partition
Command: d
Command: w

Checking File System Health

# Check file system (must be unmounted)
sudo umount /dev/nvme1n1p1
sudo fsck /dev/nvme1n1p1
 
# Check and repair
sudo fsck -y /dev/nvme1n1p1

Summary

lsblk and fdisk -l list disks and partitions
fdisk creates/deletes partitions interactively
mkfs -t ext4 formats partitions with a file system
mount/umount attach/detach partitions to directories
/etc/fstab makes mounts persistent across reboots
Always use UUID in fstab for reliability
fsck checks and repairs file systems

Next Steps

Next, we'll cover LVM (Logical Volume Manager) — flexible storage that can be resized without downtime.

Learning Objectives