This is something that hits all of IBM i community members right in the gut. That moment when the system whispers, “I’m running out of room,” and we need answers fast! WRKSYSSTS shows the ASP creeping toward 100%, the phone starts ringing, and the usual suspects (big libraries, old spool files, journal receivers) aren’t the culprits.
So… what is quietly devouring your disk space?
For years, most of us have been half-blind on IBM i. GO DISKTASKS is great for libraries, but the IFS? Good luck getting the full picture without commercial tools or writing endless scripts.
Enter a little open-source gem that should be in every IBM i admin’s toolkit in 2025: ncdu.
NookieDoo – Ncdu stands for NCurses Disk Usage. It’s a fast, interactive disk‑usage analyzer that runs in a terminal and uses the ncurses interface to make exploring disk space simple. It’s a lightweight, command‑line tool that:
- Lets you sort, drill down, and even delete files directly from the interface
- Scans directories to show where disk space is being used
- Displays results in an interactive, navigable UI
It’s free, fast, and gives you an interactive, navigable view of what’s really taking up space, libraries and IFS, all in one place.
Step 1 – Get It Installed (One-Time Thing)
Assuming you already have the open-source ecosystem set up (most of us do by now), open an SSH session (ACS, PuTTY, whatever) and run:
yum install ncduOr, if you prefer the GUI route, use the Open-Source Package Management in IBM i Access Client Solutions:
Takes seconds.
Step 2 – Start Hunting
ncdu shines when run from your SSH Terminal.
Let’s do a quick test on a single library. In my case I will run this from my terminal in VS-CODE for my personal code-sample library called (surprise surprise!) NICKLITTEN:
ncdu /QSYS.LIB/NICKLITTEN.LIBYou’ll see a sorted list — biggest objects at the top, sizes in human-readable format. Use arrow keys to move around, press ? for help.
How about hunting an IFS folder and all subfolders?
Simples! Just set the folder name and ncdu will automatically size that folder and all subfolders.
ncdu /home
Now for the real reveal — the whole system:
ncdu /It takes a while (or a long while) to scan everything (/QSYS.LIB + all IFS directories) so plan accordingly. You can easily cancel the operation by pressing q to abort at anytime. During my testing it never eat up system resources, but then again, I have my own IBM-i system so your mileage may vary. Give it a go! When it finishes… there it is. The truth. No more blind spots.
It will list all the objects its checking while it’s loading… go and make a cup of tea and sit back:
You’ll spot forgotten save files, old project directories in /home, temp files gone wild — whatever’s been hiding.
A Small Word of Caution
ncdu has a d key to delete items right there on screen.
Powerful? Yes. Dangerous if you’re in a hurry? Also yes.
My advice: use it as your forensic flashlight first. Identify the space hogs, then delete safely the old-fashioned way (or script it if you’re feeling fancy).
In 2026 with a heap of modern tools at our IBM-i fingers the old fashioned green-screen “display it to an outfile and query it” just doesn’t cut it anymore. There’s really no excuse to fly half-blind on disk space anymore. ncdu is open-source and completely free, it integrates beautifully with our IBM-i world and finally gives us the visibility users have deserved for years.
Next time the system cries “out of space,” fire up ncdu and ask the real question: “What’s actually eating my disk?”
You’ll have your answer in minutes.
Have you tried ncdu yet? Found any shocking space thieves? Drop a comment, I’d love to hear your war stories.
Happy hunting!