For the longest time! I have had an annoying issue with my Mac Studio. A little over half of my disk was being used. I have a 1TB disk. Of this roughly 266GB was used on System Data.

There are so many post about this on Apples own discussion board, on Reddit, on Ask Different, and so on. YouTube has over a 100 videos about cleaning it and so. However, none of these solved the issue for me.

I went through application data, caches, and all the other fluff. Which according to the different resources could be the potential issue. Then! I noticed something. My Time Machine had been failing since July last year. YEAH YEAH I know CHECK YOU FLIPPING BACKUPS. I do check the others, I promise!

Which made me think, what does Time Machine do with the backups it prepare? Turns out it stores some form of snap short locally on your machine. But how can you know that? Because it sure as hell, is not obvious from Time Machine settings.

Well enter tmutil. Which let you interact with time machine through the command line. If you look at the man page you will see the verb listlocalsnapshots. This let you list all local snapshots for a give mount point. To get for you Macintosh hard drive run the command tmutil listlocalsnapshots /. For me this gave me a list of 21 one snap shots:

com.apple.TimeMachine.2026-03-30-034253.local
com.apple.TimeMachine.2026-03-29-232838.local
com.apple.TimeMachine.2026-03-29-180459.local
com.apple.TimeMachine.2026-03-30-162801.local
com.apple.TimeMachine.2026-03-29-190510.local
com.apple.TimeMachine.2026-03-30-080956.local
com.apple.TimeMachine.2026-03-30-101239.local
com.apple.TimeMachine.2026-03-30-125847.local
com.apple.TimeMachine.2026-03-30-003759.local
com.apple.TimeMachine.2026-03-30-070449.local
com.apple.TimeMachine.2026-03-29-213724.local
com.apple.TimeMachine.2026-03-30-141114.local
com.apple.TimeMachine.2026-03-30-152753.local
com.apple.TimeMachine.2026-03-30-021149.local
com.apple.TimeMachine.2026-03-30-091308.local
com.apple.TimeMachine.2026-03-30-050221.local
com.apple.TimeMachine.2025-07-07-205826.local
com.apple.TimeMachine.2026-03-30-060144.local
com.apple.TimeMachine.2026-03-30-113605.local
com.apple.TimeMachine.2026-03-29-223324.local
com.apple.TimeMachine.2026-03-29-200941.local

First things first! APPLE!!!! Why are these not in order? Secondly, that is quite a lot although the do not seem to be so widely disburse. This sort of worried me because I have had my time machine hard drive connected. So why had it not taken any backups? Well that is saga for another day.

But how much space did these snapshot take? Well, honestly I did not care about what was in them, as I have other backups I know is up to date and more importantly working! So I decided to delete them ALL. No dry run no nothing! Like a pro! Or something to that extend. Turns out tmutil has a command for this called deletelocalsnapshots. Please notice the s in the end. The full command goes either tmutil deletelocalsnapshots <MOUNT POINT> or tmutil deletelocalsnapshots <DATE>. It deletes ALL snapshots from either the mount point or from the date you provide. I could not find one that actually can delete a single snapshot. So powerful tool, a true nuke! Either nuke with day precision or nuke it from orbit.

But what did this give me? Well my System Data Storage usage went from 266GB to 25.23GB so roughly a 10.5x decrease. Significant! Magnificent! So maybe you can give this a try. Though, I do urge you to be careful. In case there might be something in those snapshots you have deleted but needs.

NOW my next quest in this saga will be to find out what the hell is wrong. Is it the disk? Is it my mac? Is it macOS? A dark curse? Is it something else? Who knows? I do not. I have literally never seen Time Machine fail like this. And I have been using on the first mac I got with Mac OS X Leopard, so since 2008. Almost two decades without failure. What happened?

I will find out.