Disk Usage and Storage Monitoring in Red Hat Linux

Welcome to Day 8 of the 30 Days of Linux Challenge. Starting today, we’re using Red Hat Linux (RHEL-based environments) for all remaining sessions.

Today’s focus is one of the most crucial responsibilities of a Linux administrator: monitoring disk space and managing storage. Whether you’re running a web server, managing logs, or planning a backup routine — visibility into your system’s storage is key to keeping things running.

📚 Table of Contents

• Why Disk Management Matters
• Essential Disk Commands on RHEL
• Understanding Filesystems in Red Hat
• Monitoring and Cleaning Disk Usage
• LVM: Logical Volume Management
• Try It Yourself
• Why This Matters

Why Disk Management Matters

Disk space issues are among the top causes of system outages. In Red Hat Linux environments, this can result in:

• Services failing to start
• Logs not being written
• Software updates breaking
• Backups silently failing

Learning to monitor, analyze, and clean up your disks is a core competency for system administrators.

Essential Disk Commands on RHEL

Here are key tools and commands built into Red Hat-based systems:

📦 df – Disk Usage Overview

df -h
Shows used and available space on all mounted filesystems

-h gives human-readable sizes

📁 du – Directory Space Usage

du -sh /var/log
View how much space a directory is using

Add -a to include files, -x to stay on one filesystem

💽 lsblk – View Block Devices
lsblk
Lists physical storage devices and their partitions/mount points

🔗 mount or findmnt – See Mounted Filesystems

mount | grep '^/dev'
findmnt

🔍 blkid – Show UUIDs and Filesystem Info
sudo blkid

Understanding Filesystems in Red Hat

Red Hat commonly uses:

• XFS (default on RHEL 7+)
• ext4
• LVM for dynamic partitioning

To check filesystem type:

df -T

Monitoring and Cleaning Disk Usage

*Find large files and directories:
*
du -ahx / | sort -rh | head -20
du -sh /var/log/*

Find files over 500MB:

find / -type f -size +500M -exec ls -lh {} \; | sort -k 5 -rh | head -10

*Clean Up Space:
*🧹 Clear journal logs (default in RHEL):

sudo journalctl --vacuum-time=7d

🧹 Clear DNF/YUM cache:
sudo dnf clean all

🧹 Remove orphaned packages:
sudo dnf autoremove

LVM: Logical Volume Management

Many Red Hat systems use LVM by default. LVM allows you to resize partitions, create snapshots, and manage disks more flexibly.

View LVM status:

sudo vgs # Volume Groups
sudo lvs # Logical Volumes
sudo pvs # Physical Volumes
We’ll dive deeper into LVM configuration and resizing later in the challenge.

Try It Yourself

Open your Red Hat terminal and try:

1. df -h
2. du -sh /home/*
3. lsblk
4. sudo dnf clean all
5. sudo journalctl --vacuum-time=7d
6. sudo vgs

This will give you a full picture of your system’s current disk health.

Why This Matters

Without proper storage monitoring:

• Services fail unexpectedly
• Updates won’t apply
• You risk data loss or system crashes
• These tools are essential for troubleshooting, capacity planning, and ensuring reliability in production.