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

Stop blindly trusting your filesystem free space report

🧩 The Challenge

Ever look at df and see 10 percent disk usage, only to have your application throw ENOSPC errors because it can’t create a tiny temp file? It’s enough to make you throw your keyboard across the room when you realize the filesystem is just reserving space for the root user.

💡 The Fix

Use tune2fs to claw back that reserved block percentage so your data partition actually uses the space you paid for. You’ll save gigabytes on large drives without breaking a sweat.

tune2fs -m 1 /dev/sdb1

⚙️ Why It Works

Filesystems default to reserving 5 percent of blocks for root so the OS can keep functioning if the disk fills up, but on a 4TB storage drive, that’s a massive waste of usable space. Dialing it down to 1 percent is standard practice for non-root data disks.

🚀 Pro-Tip: Always double check your device path before running this, because fat-fingering the wrong disk will ruin your whole afternoon.

Linux Tips & Tricks | © ngelinux.com | 9/19/2026