Disk and Storage Management

Managing disks and storage is a fundamental system administration skill. This chapter will walk you through the Linux storage architecture, from viewing disk information to partitioning, formatting, and mounting, all the way to advanced topics like LVM and disk encryption.

💿 Storage Fundamentals

Storage Hierarchy

In a Linux system, data goes through several layers of abstraction from the physical hard drive to a user-accessible directory. Understanding this hierarchy will help you master all the operations that follow:

Physical Disk: The actual hard drive device installed in a server or computer, such as /dev/sda or /dev/nvme0n1
Partition: Dividing a physical disk into multiple logical regions, each used independently
Filesystem: The data organization scheme on a partition, determining how files are stored and retrieved
Mount Point: The location in the directory tree where a filesystem is "attached"; users access data through this directory

Core Terminology

Term	Description	Analogy
Hard Disk / SSD	Physical storage device	A building
Partition	Logical region carved out of a hard disk	Floors in the building
Filesystem	Data organization format on a partition	Room layout on each floor
Mount Point	Where a filesystem is attached in the directory tree	The door number to enter a floor
Block Device	Kernel abstraction representing a storage device	The building's blueprint
inode	Data structure recording file metadata in a filesystem	Registration card for each room
UUID	Globally unique identifier for a partition	Unique serial number for each room
GPT/MBR	Partition table formats (GPT is the modern format)	The standard for floor plan design

Device Naming Conventions

Different types of disks in Linux have different device names:

bash

# SATA / SCSI disks
/dev/sda        # First SATA disk
/dev/sda1       # First partition on the first SATA disk
/dev/sdb        # Second SATA disk

# NVMe solid-state drives
/dev/nvme0n1    # First NVMe disk
/dev/nvme0n1p1  # First partition on the first NVMe disk

# Virtual disks (common in virtual machines)
/dev/vda        # First virtio disk
/dev/vda1       # First partition on the first virtio disk

🔍 Viewing Disk Information

Common Commands

bash

# List all block devices in a tree structure
lsblk

# List block devices with filesystem information
lsblk -f

# View detailed partition information for all disks
sudo fdisk -l

# View disk usage for all filesystems (human-readable format)
df -h

# Show only local physical disk usage (exclude temporary filesystems)
df -h --type=ext4 --type=btrfs --type=xfs

# View the size of each subdirectory under a specific directory
du -sh /home/user/*

# View UUIDs and filesystem types of all partitions
sudo blkid

# View disk SMART health information (requires smartmontools)
sudo smartctl -a /dev/sda

Understanding lsblk Output

After running lsblk, you will see output similar to the following:

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda           8:0    0 238.5G  0 disk
├─sda1        8:1    0   512M  0 part /boot/efi
├─sda2        8:2    0   230G  0 part /
└─sda3        8:3    0     8G  0 part [SWAP]
sdb           8:16   0 931.5G  0 disk
└─sdb1        8:17   0 931.5G  0 part /mnt/data

Column descriptions:

Column	Description
`NAME`	Device name; indentation shows hierarchy (disk -> partition)
`MAJ:MIN`	Major and minor device numbers
`RM`	Whether the device is removable (1 = yes)
`SIZE`	Device capacity
`RO`	Whether the device is read-only (1 = read-only)
`TYPE`	Type: disk, part (partition), lvm (logical volume)
`MOUNTPOINTS`	Mount point path

Understanding df Output

After running df -h, you will see output similar to:

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2       230G   45G  174G  21% /
/dev/sda1       512M   12M  500M   3% /boot/efi
/dev/sdb1       932G  200G  685G  23% /mnt/data
tmpfs           3.9G   28M  3.9G   1% /dev/shm

Size: Total size of the partition
Used / Avail: Used / available space
Use%: Usage percentage; attention is needed when it exceeds 90%
Mounted on: Mount point

💡 Tip

When Use% approaches 100%, the system may behave abnormally. It is recommended to keep root partition usage below 80% during normal operation.

📊 Filesystem Types

Common Filesystem Comparison

Filesystem	Max File	Max Partition	Key Features	Recommended Use Case	Debian Recommendation
ext4	16 TB	1 EB	Stable, reliable, journaling, backward compatible	General system partitions	Default recommendation
Btrfs	16 EB	16 EB	Snapshots, compression, subvolumes, checksums	When snapshots or data checksums are needed	Recommended
XFS	8 EB	8 EB	High performance, parallel I/O, online expansion	Large files, databases	Recommended
NTFS	16 TB	256 TB	Default Windows filesystem	Sharing data in dual-boot setups	Compatible use
FAT32	4 GB	2 TB	Broadest compatibility	USB drives, EFI partitions	Special purposes only
exFAT	16 EB	128 PB	FAT without the 4 GB limit	USB drives, external storage	Compatible use
swap	—	—	Swap space	Supplement when memory is insufficient	Required

Selection Recommendations

General desktop / server: Choose ext4 — it is the Debian default filesystem with stability proven over many years
Need snapshot functionality: Choose Btrfs — supports transparent compression and snapshot rollback
Large files and databases: Choose XFS — excels at handling large files and high-concurrency I/O
Sharing data with Windows: Choose NTFS (good read-only performance) or exFAT (read-write compatible)
USB drives and boot partitions: Choose FAT32 (the EFI partition must use FAT32)

💡 Tip

If you are a beginner and unsure which to pick, go with ext4. It is the safest and most mature choice.

🔧 Partitioning Tools

fdisk (Command-Line Partitioning Tool)

fdisk is the most classic command-line partitioning tool in Linux, suitable for both MBR and GPT partition tables:

bash

# Partition /dev/sdb
sudo fdisk /dev/sdb

# Common commands in interactive mode:
# m - Display help menu
# p - Print current partition table
# n - Create a new partition
# d - Delete a partition
# t - Change partition type
# w - Write partition table and exit
# q - Quit without saving

Example of the complete interactive flow for creating a new partition:

bash

sudo fdisk /dev/sdb
# Enter n (create new partition)
# Enter p (select primary partition)
# Enter 1 (partition number)
# Press Enter (use default starting sector)
# Press Enter (use all remaining space) or enter +50G (specify size)
# Enter w (write and save)

parted (GPT-Capable Partitioning Tool)

parted is more powerful and natively supports GPT partition tables and large-capacity disks:

bash

# Partition /dev/sdb
sudo parted /dev/sdb

# Common commands in interactive mode:
# print      - Display current partition information
# mklabel gpt - Create a GPT partition table
# mkpart primary ext4 0% 100% - Create a partition spanning the entire disk
# rm 1       - Delete partition 1
# quit       - Exit

Complete partitioning in a single command (non-interactive):

bash

# Create a GPT partition table
sudo parted /dev/sdb mklabel gpt

# Create a partition spanning the entire disk
sudo parted /dev/sdb mkpart primary ext4 0% 100%

GParted (Graphical Partitioning Tool)

GParted is an intuitive graphical partition management tool, ideal for beginners:

bash

# Install GParted
sudo apt install gparted

# Launch GParted
sudo gparted

💡 Tip

Beginners are recommended to use the GParted graphical tool. It offers a more intuitive interface and lets you preview changes before applying them, helping avoid accidental mistakes.

DANGER

Partitioning operations modify disk structure. Always back up important data before proceeding. Partitioning a disk that already contains data may result in data loss.

➕ Adding a New Hard Drive

Complete Workflow

When adding a new hard drive to your system, follow this workflow:

Step-by-Step Guide

Step 1: Identify the New Hard Drive

bash

# List all block devices to find the newly added disk
lsblk

# Example output (sdb is the newly added disk, with no partitions or mount points):
# NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
# sda      8:0    0 238.5G  0 disk
# ├─sda1   8:1    0   512M  0 part /boot/efi
# ├─sda2   8:2    0   230G  0 part /
# └─sda3   8:3    0     8G  0 part [SWAP]
# sdb      8:16   0 500.0G  0 disk            ← New hard drive

Step 2: Create a Partition

bash

# Use parted to create a GPT partition table and partition (recommended)
sudo parted /dev/sdb mklabel gpt
sudo parted /dev/sdb mkpart primary ext4 0% 100%

# Or use fdisk
sudo fdisk /dev/sdb
# Then follow the interactive steps (see the fdisk section above)

Step 3: Format the Partition

bash

# Format the new partition with the ext4 filesystem
sudo mkfs.ext4 /dev/sdb1

# For other filesystems:
# sudo mkfs.btrfs /dev/sdb1    # Btrfs
# sudo mkfs.xfs /dev/sdb1      # XFS
# sudo mkfs.vfat /dev/sdb1     # FAT32

Step 4: Create a Mount Point

bash

# Create a directory for mounting
sudo mkdir -p /mnt/data

Step 5: Mount the Partition

bash

# Mount the partition to the mount point
sudo mount /dev/sdb1 /mnt/data

# Verify the mount was successful
df -h /mnt/data

Step 6: Configure Auto-Mount (fstab)

bash

# Get the partition's UUID
sudo blkid /dev/sdb1
# Example output: /dev/sdb1: UUID="a1b2c3d4-e5f6-7890-abcd-ef1234567890" TYPE="ext4"

# Edit the fstab file
sudo nano /etc/fstab

# Add a line at the end of the file (replace the UUID with your actual value):
# UUID=a1b2c3d4-e5f6-7890-abcd-ef1234567890  /mnt/data  ext4  defaults  0  2

Step 7: Verify the Configuration

bash

# First unmount the partition
sudo umount /mnt/data

# Test whether the fstab configuration is correct (mount all unmounted entries in fstab)
sudo mount -a

# Confirm the mount was successful
df -h /mnt/data

# Confirm there are no error messages
lsblk

WARNING

Be very careful when editing /etc/fstab. An incorrect configuration may prevent the system from booting properly after a restart. It is recommended to test with sudo mount -a after every modification.

📍 Mount Management

mount and umount Commands

bash

# Mount a partition to a specified directory
sudo mount /dev/sdb1 /mnt/data

# Mount in read-only mode
sudo mount -o ro /dev/sdb1 /mnt/data

# Mount with a specified filesystem type
sudo mount -t ext4 /dev/sdb1 /mnt/data

# Mount with multiple options
sudo mount -o rw,noexec,nosuid /dev/sdb1 /mnt/data

# Unmount a partition
sudo umount /mnt/data

# Force unmount if the device is busy (use with caution)
sudo umount -l /mnt/data

# View all current mount points
mount | column -t

/etc/fstab In Detail

/etc/fstab is the core configuration file that controls automatic mounting behavior at system startup:

bash

# /etc/fstab format:
# <device>         <mount point>  <type>  <options>    <dump>  <pass>
UUID=a1b2c3d4    /          ext4    defaults   0       1
UUID=e5f6a7b8    /boot/efi  vfat    umask=0077 0       1
UUID=c9d0e1f2    /mnt/data  ext4    defaults   0       2
/swapfile        swap       swap    defaults   0       0

Field descriptions:

Field	Description	Common Values
Device	Partition identifier; UUID is recommended	`UUID=xxxx`, `/dev/sdb1`
Mount Point	Path in the directory tree where it is mounted	`/mnt/data`, `/home`
Type	Filesystem type	`ext4`, `btrfs`, `xfs`, `swap`
Options	Mount options	`defaults`, `ro`, `noexec`
Dump	Whether dump backup is allowed	`0` (disabled) or `1` (enabled)
Pass	fsck check order at boot	`0` (no check), `1` (root partition), `2` (other partitions)

Common Mount Options

Option	Description
`defaults`	Equivalent to rw,suid,dev,exec,auto,nouser,async
`rw`	Read-write mode
`ro`	Read-only mode
`noexec`	Prevent execution of binaries on this partition
`nosuid`	Ignore SUID/SGID bits
`nodev`	Prevent interpretation of character or block devices on this partition
`auto`	Automatically mount at system startup
`noauto`	Do not auto-mount; requires manual mount
`nofail`	Do not report errors if the device does not exist (suitable for external drives)
`user`	Allow non-root users to mount

Use UUIDs Instead of Device Names

bash

# Get the partition's UUID
sudo blkid /dev/sdb1

# Example output:
# /dev/sdb1: UUID="a1b2c3d4-e5f6-7890-abcd-ef1234567890" TYPE="ext4"

# Use UUID in fstab (recommended approach)
UUID=a1b2c3d4-e5f6-7890-abcd-ef1234567890  /mnt/data  ext4  defaults  0  2

💡 Tip

Always use UUIDs instead of /dev/sdX device names to identify partitions. Device names (such as /dev/sdb1) may change when hard drives are added or removed, whereas UUIDs are unique identifiers for partitions and do not change.

💾 LVM Logical Volume Management

LVM Concepts

LVM (Logical Volume Manager) is a powerful disk management solution in Linux that adds a layer of logical abstraction between physical disks and filesystems, enabling flexible space management:

LVM three-layer architecture:

Layer	Abbreviation	Description
Physical Volume	PV (Physical Volume)	An actual disk partition or an entire disk
Volume Group	VG (Volume Group)	Pools multiple PVs into a single storage pool
Logical Volume	LV (Logical Volume)	Usable space carved out from a VG, similar to a traditional partition

Why Use LVM

Flexible resizing: Logical volumes can be expanded online without unmounting the filesystem
Cross-disk pooling: Multiple physical disks can be combined into a single large storage pool
Snapshot support: Supports creating volume snapshots for easy backup and testing
Easy management: After adding a new disk, simply extend the volume group to increase available space

Installing LVM Tools

bash

# Install the LVM2 toolset
sudo apt install lvm2

Complete LVM Creation Workflow

bash

# Step 1: Create Physical Volumes (PV)
sudo pvcreate /dev/sdb1 /dev/sdc1

# View physical volume information
sudo pvs
sudo pvdisplay

# Step 2: Create a Volume Group (VG) named vg-data
sudo vgcreate vg-data /dev/sdb1 /dev/sdc1

# View volume group information
sudo vgs
sudo vgdisplay

# Step 3: Create a Logical Volume (LV) named lv-home, size 50 GB
sudo lvcreate -L 50G -n lv-home vg-data

# View logical volume information
sudo lvs
sudo lvdisplay

# Step 4: Format the logical volume
sudo mkfs.ext4 /dev/vg-data/lv-home

# Step 5: Mount the logical volume
sudo mkdir -p /mnt/home
sudo mount /dev/vg-data/lv-home /mnt/home

# Step 6: Add to fstab for auto-mounting
# First get the UUID
sudo blkid /dev/vg-data/lv-home
# Then edit /etc/fstab and add:
# UUID=xxxx  /mnt/home  ext4  defaults  0  2

Extending a Logical Volume

bash

# Extend the logical volume by 10 GB
sudo lvextend -L +10G /dev/vg-data/lv-home

# Extend the filesystem to use the new space
sudo resize2fs /dev/vg-data/lv-home

# Or complete the extension in one step (recommended), using all remaining space in the volume group
sudo lvextend -l +100%FREE /dev/vg-data/lv-home
sudo resize2fs /dev/vg-data/lv-home

# For XFS filesystems, use xfs_growfs instead of resize2fs
# sudo xfs_growfs /mnt/home

Adding a New Disk to a Volume Group

bash

# Create a physical volume from the new disk
sudo pvcreate /dev/sdd1

# Add the new physical volume to the existing volume group
sudo vgextend vg-data /dev/sdd1

# View available space in the volume group
sudo vgs

WARNING

Shrinking a logical volume is a high-risk operation. The ext4 filesystem supports shrinking but must be unmounted first, while XFS does not support shrinking at all. It is recommended to only perform this when necessary, and always back up data before proceeding.

🔄 Swap Space

Swap Partition vs. Swap File

Feature	Swap Partition	Swap File
Creation method	Requires a dedicated partition	Creates a file on an existing filesystem
Flexibility	Requires repartitioning to resize	Can be created, deleted, or resized at any time
Performance	Slightly better (direct disk access)	Nearly identical (modern kernels are optimized)
Use case	Fixed configuration planned during installation	When swap needs to be added or adjusted later
Recommendation	Traditional approach	Recommended approach for Debian 13

Creating a Swap File

bash

# Create a 4 GB swap file
sudo fallocate -l 4G /swapfile

# If fallocate is not available (some filesystems do not support it), use dd:
# sudo dd if=/dev/zero of=/swapfile bs=1M count=4096

# Set the correct permissions (only root can read and write)
sudo chmod 600 /swapfile

# Initialize the file as swap format
sudo mkswap /swapfile

# Enable the swap file
sudo swapon /swapfile

# Verify that swap is enabled
swapon --show

# Add to fstab for automatic activation at boot
echo '/swapfile swap swap defaults 0 0' | sudo tee -a /etc/fstab

Recommended Swap Size

Physical Memory	Recommended Swap Size	With Hibernation
Under 2 GB	2x the memory	3x the memory
2 - 8 GB	Same as memory	2x the memory
8 - 64 GB	4 - 8 GB	1.5x the memory
Over 64 GB	4 GB (or none)	Hibernation not recommended

Adjusting Swappiness

The swappiness parameter controls the kernel's tendency to move data from memory to swap, with a range of 0-100:

0: Avoid using swap as much as possible (only use when memory is critically low)
10: Recommended value for desktop systems
60: Debian default value
100: Aggressively use swap

bash

# View the current swappiness value
cat /proc/sys/vm/swappiness

# Temporarily change (resets after reboot)
sudo sysctl vm.swappiness=10

# Permanently change
echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf

# Apply immediately
sudo sysctl -p

💡 Tip

Desktop users are recommended to set swappiness to 10. This way, the system will prioritize using physical memory, reducing unnecessary disk read/write operations and improving system responsiveness.

🧹 Disk Space Cleanup

Common Cleanup Commands

bash

# Clean APT package cache
sudo apt clean           # Delete all downloaded .deb packages
sudo apt autoclean       # Delete only outdated .deb packages
sudo apt autoremove      # Remove dependencies that are no longer needed

# Clean old kernels (free up /boot space)
sudo apt autoremove --purge

# Limit systemd journal size
sudo journalctl --vacuum-size=100M    # Limit journal to 100 MB
sudo journalctl --vacuum-time=7d      # Keep only the last 7 days of logs

# Clean temporary files
sudo rm -rf /tmp/*
sudo rm -rf /var/tmp/*

# Find the largest files and directories on the system
sudo du -ah / --exclude=/proc --exclude=/sys | sort -rh | head -20

# Find files larger than 100 MB
sudo find / -type f -size +100M -exec ls -lh {} \; 2>/dev/null

# Clean user cache
rm -rf ~/.cache/thumbnails/*

Automated Cleanup Script

Create a simple disk cleanup script at /usr/local/bin/disk-cleanup.sh:

bash

#!/bin/bash
# Disk cleanup script - Debian 13
# Usage: sudo bash /usr/local/bin/disk-cleanup.sh

echo "===== Disk Cleanup Started ====="
echo ""

# Show disk usage before cleanup
echo "--- Disk Usage Before Cleanup ---"
df -h /

# Clean APT cache
echo ""
echo "--- Cleaning APT Cache ---"
sudo apt clean
sudo apt autoclean
sudo apt autoremove -y

# Clean old logs
echo ""
echo "--- Cleaning Old Logs ---"
sudo journalctl --vacuum-size=100M

# Clean temporary files
echo ""
echo "--- Cleaning Temporary Files ---"
sudo rm -rf /tmp/*
sudo rm -rf /var/tmp/*

# Show disk usage after cleanup
echo ""
echo "--- Disk Usage After Cleanup ---"
df -h /

echo ""
echo "===== Disk Cleanup Complete ====="

bash

# Grant execute permission
sudo chmod +x /usr/local/bin/disk-cleanup.sh

# Run the script
sudo /usr/local/bin/disk-cleanup.sh

🔐 Disk Encryption (LUKS)

LUKS (Linux Unified Key Setup) is the standard disk encryption solution for Linux, used to protect data stored on disk.

Installing Encryption Tools

bash

sudo apt install cryptsetup

Encrypting a New Partition

bash

# Step 1: Format the partition as LUKS encrypted format (this erases all data on the partition)
# You will be prompted to enter and confirm an encryption passphrase
sudo cryptsetup luksFormat /dev/sdb1

# Step 2: Open (unlock) the encrypted partition, mapping it to /dev/mapper/encrypted
sudo cryptsetup open /dev/sdb1 encrypted

# Step 3: Create a filesystem on the decrypted device
sudo mkfs.ext4 /dev/mapper/encrypted

# Step 4: Mount the encrypted partition
sudo mkdir -p /mnt/secure
sudo mount /dev/mapper/encrypted /mnt/secure

# You can now read and write files to /mnt/secure as usual

Closing an Encrypted Partition

bash

# First unmount the filesystem
sudo umount /mnt/secure

# Close (lock) the encrypted partition
sudo cryptsetup close encrypted

Auto-Mounting an Encrypted Partition at Boot

If you need to automatically mount an encrypted partition at startup (a passphrase prompt will appear during boot):

bash

# Get the UUID of the encrypted partition
sudo blkid /dev/sdb1

# Edit /etc/crypttab and add:
# encrypted  UUID=xxxx  none  luks

# Edit /etc/fstab and add:
# /dev/mapper/encrypted  /mnt/secure  ext4  defaults  0  2

WARNING

If you forget the encryption passphrase, the data cannot be recovered. Make sure to keep your passphrase safe, and consider recording a backup passphrase in a secure location.

DANGER

The cryptsetup luksFormat command completely erases all data on the target partition. Make sure important data has been backed up before executing this command.

🏥 SMART Disk Health Monitoring

What is SMART

SMART (Self-Monitoring, Analysis and Reporting Technology) is a built-in health monitoring technology in hard drives that can provide early warnings of potential drive failures.

Installation and Usage

bash

# Install smartmontools
sudo apt install smartmontools

# View full SMART information for a disk
sudo smartctl -a /dev/sda

# Quick health check (returns PASSED or FAILED)
sudo smartctl -H /dev/sda

# View the disk's error log
sudo smartctl -l error /dev/sda

# Run a short self-test (approximately 2 minutes)
sudo smartctl -t short /dev/sda

# Run a long self-test (may take several hours)
sudo smartctl -t long /dev/sda

# View self-test results
sudo smartctl -l selftest /dev/sda

Key SMART Indicators

Indicator	Description	Warning Threshold
`Reallocated_Sector_Ct`	Number of reallocated sectors	Greater than 0 requires attention
`Current_Pending_Sector`	Sectors currently pending reallocation	Greater than 0 requires attention
`Offline_Uncorrectable`	Uncorrectable offline sectors	Greater than 0 requires attention
`UDMA_CRC_Error_Count`	Data transfer error count	Check cables if continuously increasing
`Temperature_Celsius`	Drive temperature	Improve cooling if above 55 C
`Power_On_Hours`	Total powered-on time	For reference only

Configuring Automatic Monitoring

bash

# Enable the smartd daemon (automatically monitors all disks)
sudo systemctl enable smartd
sudo systemctl start smartd

# Edit the smartd configuration file to customize monitoring rules
sudo nano /etc/smartd.conf

# Example configuration: monitor /dev/sda and send email when issues are found
# /dev/sda -a -o on -S on -s (S/../.././02|L/../../6/03) -m [email protected]

💡 Tip

It is recommended to check SMART status at least once a month. When Reallocated_Sector_Ct or Current_Pending_Sector is non-zero, you should back up your data promptly and prepare to replace the drive.

🚨 Troubleshooting

Disk Space Full

bash

# Check overall disk usage
df -h

# Find which directories are using the most space
sudo du -sh /* | sort -rh | head -10

# Drill further into the largest directory
sudo du -sh /var/* | sort -rh | head -10

# Find large files created in the last 7 days
sudo find / -type f -size +50M -mtime -7 -ls 2>/dev/null

# Check inode usage (too many small files can also cause a "full disk" error)
df -i

Unable to Mount a Partition

bash

# Check if the filesystem is corrupted (partition must be unmounted first)
sudo fsck /dev/sdb1

# Check system logs for error messages
sudo dmesg | tail -30
sudo journalctl -xe

# Check if the fstab configuration is correct
cat /etc/fstab

# Try mounting manually and check for error messages
sudo mount -v /dev/sdb1 /mnt/data

Filesystem Error Repair

bash

# Important: the filesystem must be unmounted before repair
sudo umount /dev/sdb1

# Check and repair an ext4 filesystem
sudo fsck.ext4 -f /dev/sdb1

# Check and repair an XFS filesystem
sudo xfs_repair /dev/sdb1

# Check and repair a Btrfs filesystem
sudo btrfs check /dev/sdb1

DANGER

Never run fsck on a mounted filesystem! This can cause severe data corruption. If you need to repair the root partition, boot from a Live USB first.

Abnormal Disk Read/Write Speed

bash

# Simple disk write speed test
dd if=/dev/zero of=/tmp/testfile bs=1M count=1024 oflag=direct 2>&1

# Simple disk read speed test
dd if=/tmp/testfile of=/dev/null bs=1M count=1024 iflag=direct 2>&1

# Clean up the test file
rm /tmp/testfile

# Test read speed using hdparm
sudo apt install hdparm
sudo hdparm -tT /dev/sda

# Check disk I/O status
sudo apt install sysstat
iostat -x 1 5

📝 Practical Tips Summary

Quick Reference

Task	Command
View all disks	`lsblk`
View disk usage	`df -h`
View directory size	`du -sh /path`
View partition UUID	`sudo blkid`
Format as ext4	`sudo mkfs.ext4 /dev/sdX1`
Mount a partition	`sudo mount /dev/sdX1 /mnt/point`
Unmount a partition	`sudo umount /mnt/point`
Test fstab	`sudo mount -a`
Extend LVM	`sudo lvextend -L +10G /dev/vg/lv && sudo resize2fs /dev/vg/lv`
Create swap file	`sudo fallocate -l 4G /swapfile`
Disk health check	`sudo smartctl -H /dev/sda`
Filesystem repair	`sudo fsck /dev/sdX1` (must unmount first)

Safety Checklist

Before performing disk operations, verify the following items:

Back up data: Before any partitioning or formatting operation, ensure important data has been backed up
Confirm device name: Use lsblk repeatedly to confirm the device you are about to operate on, to avoid accidentally modifying the system disk
Unmount before operating: The filesystem must be unmounted before repair
Test fstab: After modifying /etc/fstab, validate with mount -a
Use UUIDs: Always use UUIDs in fstab, not /dev/sdX
Keep passphrases safe: Store encryption passphrases securely

Next Steps

After mastering disk and storage management, you can continue learning:

Backup & Recovery - Protect your data with backup strategies
Security Hardening - Strengthen system security
Network Configuration - Configure and manage network settings

Disk management mastered? Continue to Backup & Recovery →

Disk and Storage Management ​

💿 Storage Fundamentals ​

Storage Hierarchy ​

Core Terminology ​

Device Naming Conventions ​

🔍 Viewing Disk Information ​

Common Commands ​

Understanding lsblk Output ​

Understanding df Output ​

📊 Filesystem Types ​

Common Filesystem Comparison ​

Selection Recommendations ​

🔧 Partitioning Tools ​

fdisk (Command-Line Partitioning Tool) ​

parted (GPT-Capable Partitioning Tool) ​

GParted (Graphical Partitioning Tool) ​

➕ Adding a New Hard Drive ​

Complete Workflow ​

Step-by-Step Guide ​

Step 1: Identify the New Hard Drive ​

Step 2: Create a Partition ​

Step 3: Format the Partition ​

Step 4: Create a Mount Point ​

Step 5: Mount the Partition ​

Step 6: Configure Auto-Mount (fstab) ​

Step 7: Verify the Configuration ​

📍 Mount Management ​

mount and umount Commands ​

/etc/fstab In Detail ​

Common Mount Options ​

Use UUIDs Instead of Device Names ​

💾 LVM Logical Volume Management ​

LVM Concepts ​

Why Use LVM ​

Installing LVM Tools ​

Complete LVM Creation Workflow ​

Extending a Logical Volume ​

Adding a New Disk to a Volume Group ​

🔄 Swap Space ​

Swap Partition vs. Swap File ​

Creating a Swap File ​

Recommended Swap Size ​

Adjusting Swappiness ​

🧹 Disk Space Cleanup ​

Common Cleanup Commands ​

Automated Cleanup Script ​

🔐 Disk Encryption (LUKS) ​

Installing Encryption Tools ​

Encrypting a New Partition ​

Closing an Encrypted Partition ​

Auto-Mounting an Encrypted Partition at Boot ​

🏥 SMART Disk Health Monitoring ​

What is SMART ​

Installation and Usage ​

Key SMART Indicators ​

Configuring Automatic Monitoring ​

🚨 Troubleshooting ​

Disk Space Full ​

Unable to Mount a Partition ​

Filesystem Error Repair ​

Abnormal Disk Read/Write Speed ​

📝 Practical Tips Summary ​

Quick Reference ​

Safety Checklist ​

Next Steps ​

Disk and Storage Management

💿 Storage Fundamentals

Storage Hierarchy

Core Terminology

Device Naming Conventions

🔍 Viewing Disk Information

Common Commands

Understanding lsblk Output

Understanding df Output

📊 Filesystem Types

Common Filesystem Comparison

Selection Recommendations

🔧 Partitioning Tools

fdisk (Command-Line Partitioning Tool)

parted (GPT-Capable Partitioning Tool)

GParted (Graphical Partitioning Tool)

➕ Adding a New Hard Drive

Complete Workflow

Step-by-Step Guide

Step 1: Identify the New Hard Drive

Step 2: Create a Partition

Step 3: Format the Partition

Step 4: Create a Mount Point

Step 5: Mount the Partition

Step 6: Configure Auto-Mount (fstab)

Step 7: Verify the Configuration

📍 Mount Management

mount and umount Commands

/etc/fstab In Detail

Common Mount Options

Use UUIDs Instead of Device Names

💾 LVM Logical Volume Management

LVM Concepts

Why Use LVM

Installing LVM Tools

Complete LVM Creation Workflow

Extending a Logical Volume

Adding a New Disk to a Volume Group

🔄 Swap Space

Swap Partition vs. Swap File

Creating a Swap File

Recommended Swap Size

Adjusting Swappiness

🧹 Disk Space Cleanup

Common Cleanup Commands

Automated Cleanup Script

🔐 Disk Encryption (LUKS)

Installing Encryption Tools

Encrypting a New Partition

Closing an Encrypted Partition

Auto-Mounting an Encrypted Partition at Boot

🏥 SMART Disk Health Monitoring

What is SMART

Installation and Usage

Key SMART Indicators

Configuring Automatic Monitoring

🚨 Troubleshooting

Disk Space Full

Unable to Mount a Partition

Filesystem Error Repair

Abnormal Disk Read/Write Speed

📝 Practical Tips Summary

Quick Reference

Safety Checklist

Next Steps