Disk & Filesystem Management (Du/Df/Lsblk/Fstrim)

Find the mount point hogging your space

🧩 The Challenge

You run df -h and see a partition is 95% full, but running du on the root directory shows way less usage. It is maddening because you know the space is gone, but the filesystem just won’t show you where it’s hiding.

💡 The Fix

The culprit is almost certainly a file that was deleted while a process still had it open, or you have a mount point hiding actual data in a directory that is now covered by a different filesystem. You need to identify the mount point and verify the true disk layout before you start deleting logs you actually need.

lsblk -f -o NAME,FSTYPE,SIZE,MOUNTPOINT

⚙️ Why It Works

By visualizing the block device tree, you can quickly spot if your expected mount points are actually active or if you have nested partitions confusing the standard directory crawl. It bypasses the abstraction of the filesystem and shows you exactly how the kernel sees the storage.

🚀 Pro-Tip: If df and du still disagree after checking mounts, use lsof | grep deleted to find those ghost files holding onto your disk space.

Linux Tips & Tricks | © ngelinux.com | 10/17/2026