MacOS 27 will solve System Data bloat???

Wasn’t true for me I just worked with Apple support for a week regarding system data bloat on brand new Mac Mini. Mine kept climbing by 10gb daily up to 167gb system data on a 512gb SSD it’s maddening. They said it’s fine and supposed to do this? everytime I plug in non Time Machine external ssd system data climbs to over 160 and when I unplug it drops to 60gb I’ve never experienced this but it’s frustrating to buy brand new system and for Mac to take hostage 100gb IMO.

This is now a few days old, and I don't know whether you're still looking at this, but the biggest problem with macOS, IMHO, is the way that Time Machine works. When I first got my Mac, I let Time Machine do frequent backups to an external drive. For some bizarre reason beyond my comprehension, Apple makes a copy of the backup on the internal drive, which creates ridiculous amounts of "System Data." Why, I ask rhetorically, am I making an external backup if I want a copy on my Mac? Bizarre! The best solution is to set Time Machine to manual backups and - when complete - immediately go into Disk Utility and get rid of the duplicate on the internal drive. I was able to regain many GBs of space that way, and still have the external backup. I hope this helps with your situation.

Ask Gemini, Claude, or ChatGPT how do this and you'll get clear instructions.

Interesting thing happened after reading many replays over the past month with System Data, I ejected my two hard drives after reading some peoples Data went down and mine went from 250GB to 90 GB just by ejected them.

Barney-15E wrote:

“Free” and “Available” are not the same. Free is a subset of Available.

Actually, in macOS 27 'free' and 'available' are the same. macOS no longer treats 'purgeable' data as part of available space, which was the reason for the difference in macOS 26 and before.

mhb wrote:

I almost never clear histories etc. But when I just cleared the history and extensions of my most used profile, precious little changed in System Data.

Remember that "deleted" files are a big source of "System Data". It will take the system a day or two to purge deleted files. So don't expect any immediate relief from deleting files. If anything, your System Data will increase.

I'm starting to think that they way I function in 2026 -- not just the browser -- is just going to require a lot more disk space for "System Data" than six years ago, unless I want my life to become about computer maintenance. So I'm back to considering a new computer with a tedious, manual, clean install of apps, profiles and preferences on a 1 TB drive for the next six or so years. Maybe this is something many are dealing with, whether they know it yet or not.

I would consider a 1 TB to be a minimum for any kind of professional usage. I keep 100 GB free and I don't have any problems.

The alternative is getting a software program to help, which can be a bit of a crapshoot if you're not familiar with these and some are dodgy.

Hopefully mine doesn't look dodgy.

melvin3v wrote:

If “System Data” is meaningless, what’s the point of showing it?

Not my call.

just go to Reddit and type in System data lol!

Thanks for the suggestion, but I'll pass.

Why hide what’s taking up that space instead of showing us what can safely be removed? Telling us to ignore it doesn’t solve the problem.

We can't do anything to solve a problem involving something that someone else (like Apple) is doing or saying. We can only control our own response to it.

Hence my suggestion to ignore the display where Apple is saying the most outlandish things. It's really not too different than social media. If you find a place where people are making the most outlandish, unhelpful, and hateful comments, don't go there anymore. Or if you do, try to avoid known sources of harm and misinformation.

And regarding your last line about fixing low storage: I currently have over 200 GB free.

Then you're good. There's nothing else you need to do. I try to keep 100 GB free. That gives me a nice buffer from the danger zone of > 50 GB where performance starts to suffer.

I’m questioning why another 167 GB is lumped into a catch-all category I can’t meaningfully manage. That’s a lot of space, especially when I have zero iOS backups and found no local Time Machine snapshots when checking in Terminal.

If macOS is supposed to manage that space automatically, why can’t it explain what it’s keeping and why? How about some transparency instead of “trust me, bro”? 🤷🏼‍♂️ Just my thoughts 👍🏻

I cannot provide any transparency. I don't work for Apple. All I can do is provide my own thoughts. All you can do is trust me, bro. 😄

It does seem like Apple's approach is that the user paid for this storage, unused storage is wasting the user's money. That's definitely the case with RAM. That approach was a significant problem about a decade ago when it was first introduced. Back then, when an iMac hit swap space, it hit a spinning platter and it stopped dead in its tracks. With modern SSDs, it's all much smoother.

But that logic hasn't translated very well to storage. Running out of storage is much like running out of RAM without virtual memory. There's just nowhere else to go. Hoping to off-load some of that to the cloud is slower than a spinning hard drive and less effective.

I did develop an app to help people manage storage. There are a handful of similar apps, but only a handful, with a couple of fingers left over. I try hard to help people recognize which files can be safely removed. But that's also a hard problem. It's been many years since Time Machine local snapshots were a leading cause of storage problems. These days, it's all over the charts. Could be anything really.

melvin3v wrote:

I have 170GB of System Data bloat with over 225GB of free disk space on macOS 27.0.1, so it just bloats regardless. And mine is brand new, only 10 days old. That only shows when my external SSD is plugged in. Immediately after ejecting it, System Data drops to 67GB.

I don't know what else to tell you. System Data is a figment of Apple's imagination. It. Does. Not. Ex. Ist.

All indications are that it's some misnaming of "other data" from Spotlight's index. But that data is only (supposed) to pertain to the startup drive. This is the first I've heard of external drives being involved. I'm not saying you're wrong. I've seen several reproducible bugs that other people couldn't reproduce. But all that being said, there are certain well-known aspects of certain technologies that strongly seem to contradict what you're describing.

Apple engineers advised me that macOS is creating one snapshot in case my external APFS drive becomes corrupt or isn’t ejected properly. They ran full diagnostics, and that’s what they reported back to me.

That's not true. For one thing, as I mentioned above, external storage doesn't apply. For another thing, snapshots themselves only consume a very negligible amount of storage - megabytes, not gigabytes. And finally, I have lots of external volumes. If what they said were true, I'd have snapshots all over the place. I have none.

What is the nature of this external drive? Is it used for Time Machine or a 3rd party backup. That might complicate matters. Perhaps that would confuse Spotlight. Spotlight is very easily confused. But again, we circle back to my first point. None of it exists. It's like people who get upset at the "Tauriel" character in "The Hobbit" movies saying she didn't exist. Well, none of them exist. It's a work of fiction, much like System Settings > Storage. The biggest difference is that Tolkien's stories are delightful fables that bring joy and entertainment to children and adults alike. The macOS Storage display - not so much.

It’s annoying, and yes, it’s purgeable space

Purgeable space does not exist.

How do I know this? There are many reports here in the forums of people trying to download a new OS update or perform some other kind of large-scale data operation. The operation fails because they don't have enough free storage. "But, but, but", they say, "it says I have 49 caboodles available! That means I must have at least 40 caboodles of purgeable storage." They tried some operation that needed 12 caboodles of purgeable caboodle storage and the operating system simply said, "no". Therefore, those caboodles weren't ever "purgeable", were they?

"Purgeable space" is another way of saying "used storage". If you need it for something, you can't have it. What else works this way? Used storage.

you shouldn’t have to buy a brand-new computer only to have macOS automatically take up a huge chunk of your storage and then basically say, “Well, you can have it back once your hard drive starts running out of space.”

I think that’s ridiculous.

It is ridiculous... because you can't have that storage back 😄.

All caboodle jokes aside, purgeable storage is used storage. It's used for things like caches that aren't strictly required. They simply speed up normal operation. You can delete them (well, not really). After a couple of days, if you try really hard, you might be able to make them go away and recover that precious 14 GB of storage that you need for that Oh So Precious operating system update. Yesssss. My precissoussss. (You see what you started? Bagginses stole our storage. Tricksy hobbittses! We hates bagginses forever.) You can't defeat the power of The One Ring forever. Sauron's deadly caches will regroup in the shadows, slowly, and one day, when you least expect it, burst forth from Minas Morgul with terrible new flame and gigabytes of usage.

But if you ever get tired of this fantasy, and desire a more solid grounding in reality, then stop looking at System Settings > Storage. It's not true. But can you handle the truth? The macOS file system is horribly complicated. You can dig into it and learn how it works if you want. Or you can take a shortcut with a 3rd party storage management tool. Or you can live behind the Storage looking glass if you really want that. One drive makes your storage big and one drive makes it small. And System Settings > Storage doesn't do anything at all.

Yup, see! I’m glad I’m not the only one experiencing this. I’ve been reporting the exact same behavior on macOS 27, and others on Reddit have confirmed it too. I love how some people on here insist this can’t happen. I said just wait until more people start reporting it! 😂

One question: Did you check Disk Utility to see whether that extra System Data was listed as purgeable space?

Actually, in macOS 27 'free' and 'available' are the same. macOS no longer treats 'purgeable' data as part of available space, which was the reason for the difference in macOS 26 and before.

That is interesting, but I thought mhb was still on Tahoe.

I did notice with OS27 that when I plug in an external drive it consumes about 16GB more of the system data. This is also different than with OS26. Seems like with every new OS more space is needed.