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:
- df -h
- du -sh /home/*
- lsblk
- sudo dnf clean all
- sudo journalctl --vacuum-time=7d
- 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.