MacOS 27 will solve System Data bloat???

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.

melvin3v wrote:

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.

It's important to remember that "System Data" is absolutely meaningless. Anything you see on System Settings > Storage is meaningless. Don't look at it.

If you're running low on free storage, that's what you need to fix. But don't even look at nonsense.

If “System Data” is meaningless, what’s the point of showing it? Mine reports 167 GB, but Apple doesn’t give us a clear breakdown or a straightforward way to manage it. I’ve owned Macs since the PowerBook G4, and I never had this much space tied up like this on my older machines and it's the worst ive seen just go to Reddit and type in System data lol!

When we spend this much on a computer, having so much of the storage we paid for tied up without a clear explanation or control is frustrating. 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.

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

etresoft wrote:

These days, it's all over the charts. Could be anything really.

That's the problem with using the Storage settings pane. Spotlight is good at finding a file for you, but bad at cataloging a disk. RAW image files are Documents, not Photos. The local cache for my work cloud storage data (200 GB) is Applications. Not to mention all the random stuff that Spotlight can't categorize and is lumped into System Data.

Preaching to the choir here, I know.

neuroanatomist wrote:

Spotlight is good at finding a file for you, but bad at cataloging a disk.

I would say it's better at cataloging a disk than finding a file. Spotlight will randomly fail to find specific files. I've got one folder that it refuses to index for some reason. I only found that by accident. How many other folders are mysteriously excluded that I don't know about?

But if you did, for some reason, what to categorize (almost) all of the files on your disk as applications, books, documents, images, messages, photos, and mail, the Spotlight will do a reasonable job of that. On the aggregate, it doesn't matter if Spotlight misses a few files or folders. It's just that this data isn't useful. So what if I have 493.2 MB of data in messages? How does that help with my 136.31 GB of System Data?

And System Data is even worse. I understand the need for an "other" category, but not with this name. It's like if you tried to use System Settings > Storage and asked, "why is my messages so big?" And Apple responds, "because you have so many Excel documents". But Excel documents aren't messages. Why aren't they classified as Excel documents? I've spent 3 days searching my messages and couldn't find any problem! And 5 years later, Apple still hasn't responded.

It just doesn't make any sense. It's not even internally consistent. It's like Apple is taking ownership of all "other" data on the computer through this name. These days, it's often (but not always) some 3rd party product causing the problem. So, understandably, people come here and ask why the latest "system" is so big. And we're left holding the bag trying to explain it to them.

Oh, now you've got me started....

I have 157 GB of free storage on this computer, so I'm good. I don't have the 302 GB that Apple claims, but I'm still good.

Apple recommends that I store all my documents in iCloud. But I have optimization disabled on this computer specifically so I have a local copy of iCloud data.

Apple tells me I can save space by automatically removing movies and TV shows that I'm already watched. I don't have any movies or TV shows.

Apple tells me I can save space by automatically emptying the trash. But right below that, Apple helpfully tells me that I have 113.9 MB in the trash. I don't think that's going to meaningfully impact storage on my 1 TB drive.

Apple does tell me that I have 11.61 GB of data in Apple Intelligence. But this is on Sequoia, where I still have a button to turn off Apple Intelligence. And it is definitely "off".

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.

That sounds like there is about 100 GB of stuff on the external that Spotlight hasn’t indexed or can’t identify.

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.

Sounds plausible.

So according to them, it’s completely normal, but IMO, it’s ridiculous. They could easily fix this, or maybe they just aren’t smart enough to properly label everything and be transparent. Who knows? 😂

There are lots of things that are not one of the listed categories, possibly because very few people care what they are.

It’s annoying, and yes, it’s purgeable space, but 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.”

If it goes away when you eject the drive, is it really taking up a “chunk of space?” An SSD cannot instantly reset the storage to make it useable immediately. If it magically disappears, it isn’t being taken away from you.

If it is a snapshot per Apple support, it likely is reporting the storage required if the snapshot was fully materialized on disk, not what it is actually used on disk.

Just my opinion. You’re ok with that, right?

Just to clarify, I actually have my external SSD specifically excluded from Spotlight indexing under the Spotlight Search Privacy settings, so Spotlight isn’t indexing that drive at all.

As for your explanation about macOS possibly reporting how much space a snapshot would require if it were fully stored rather than how much physical space it’s actually consuming, that does sound plausible. It could explain why the System Data figure changes so dramatically when I connect or eject the drive.

I actually asked the Apple engineers specifically why this happens almost instantly on my Mac. The engineer explained that on an older or slower Mac, or one with significantly more data on it, this process could happen gradually over the course of 3 to 5 days, so people might not even notice it happening. However, because my Mac is brand new, has very little data on it, and has extremely fast hardware, he said the process happens almost instantly.

Apple engineering ran full diagnostics and specifically reported back that macOS is creating a snapshot associated with my external APFS drive. That’s the explanation they gave me after investigating the issue.

I understand your point about the difference between reported storage and actual physical space being consumed, and I think it’s a reasonable possibility. I’m not claiming that 100GB is necessarily being permanently taken away from me.

My biggest frustration is that macOS reports roughly 170GB of System Data on a brand-new computer, then drops to around 67GB immediately after ejecting the external SSD, without clearly explaining what that additional 100GB actually represents. Whether it’s physically consuming that space or simply reporting the potential size of a snapshot, Apple should be much more transparent about it.

If the space isn’t actually being used, why display it in a way that makes it appear as though it is? That’s really my point. 😂

melvin3v wrote:

Just to clarify, I actually have my external SSD specifically excluded from Spotlight indexing under the Spotlight Search Privacy settings, so Spotlight isn’t indexing that drive at all.

That’s the whole point. If it cannot use Spotlight to determine what it is, it is all System Data.

If the space isn’t actually being used, why display it in a way that makes it appear as though it is? That’s really my point. 😂

The space is being used,

…on your external drive.

I always advise to never use the dynamically generated storage displays because they are infinitely confusing and mostly useless.

melvin3v wrote:

In my case, CleanMyMac...

Probably unwise. Long-time members here often refer to that piece of crapware as BrickMyMac, based on the number of problems it causes, especially after macOS updates.

melvin3v wrote:

In my case, CleanMyMac

Perhaps we're getting closer to the answer now.

I'm not one to disparage CleanMyMac that way other people do here in the forums. From what I see, it causes relatively few problems compared to how ubiquitous it is. But it most definitely is a "clean up" app. Technically speaking, you aren't having a problem. You're just poking around a little too deeply. CleanMyMac could be the cause of this strange behaviour with its "clean up" activities. All those "caches" and "junk" that it deletes will immediately become "System Data" until the system deletes it. And then, the system gets right back to work rebuilding all of it, which CleanMyMac will later dutifully delete again. Lather, rinse, repeat.

DaisyDisk were unable to locate the hidden System Data.

To get back to my previous point, that's like hiring an expert nature guide and asking him to guide you to Mirkwood forest. He can't find Mirkwood forest because it doesn't actually exist.

There are other forests you could explore, and many of them may have some very interesting flora and fauna. But if you want to explore, you have to stay grounded in the real world, not the make-believe one.

I migrated from an M1 MacBook Air with only a 256GB SSD annd 109gb free and there’s hardly anything on either computer. My Mac mini has a 512GB SSD with about 225GB free, yet System Data jumps to around 165GB whenever my external SSD is plugged in. As soon as I unplug it and reopen Storage settings, System Data drops back down to around 60GB.

I want to reiterate an important point here. Storage problems, especially "System Data" problems are one of the most commonly reported problems with macOS over the past several years. It's a major, major problem.

But in that all that time, you are the one person to report this specific behaviour. No one else - not even once.

Apple engineers told me this is normal behavior, which is frustrating. They were pretty firm in their explanation that macOS 27 creates a hidden snapshot in case the external SSD becomes corrupted or is improperly ejected. Whether that’s BS or not, I have no idea, but they spent a 3 days investigating before getting back to me with that explanation or that’s at least when supervisors responded 👍 And this is Os27 for me OP is on Tahoe I beleive.

A local snapshot isn't going to consume 100 GB. It's simply not possible.

melvin3v wrote:

In my case, CleanMyMac ... System Data jumps to around 165GB whenever my external SSD is plugged in. As soon as I unplug it and reopen Storage settings, System Data drops back down to around 60GB.

As @etresoft points out, that's not supposed to happen. Period. If that's what you see on your Mac, then there is something very odd with your Mac. I would guess that BrickMyMac is part of the problem, for sure it's not part of the solution.

You state that plugging in an external SSD makes your System Data jump by over 100 GB. As a benchmark, on Golden Gate 27.0.1, my System Data has been between 150-160 GB. I use many external SSDs, and I have never seen System Data change when mounting or ejecting any of them. So I decided to mount more than one.

Top to bottom on the right of System Settings, that's my 2 TB internal drive, a small locally-saved disk image, five external SSDs (a mix of Samsung T7 and T9 1 TB and 2 TB drives), and for good measure an SD card in the MBP's internal slot (shows as an SD card icon) and another SD card in the slot on my Thunderbolt dock. With all of those drives/cards mounted, System Data is showing as 152.76 GB.

I then quit System Settings, ejected all the mounted drives (and unplugged/removed the 7 external ones), re-launched System Settings and clicked on Storage, and waited a few seconds for System Data to finish calculating.

No change. Well, technically it went from 152.76 GB to 152.77 GB. It's definitely not >100 GB smaller after ejecting all the external storage media.

Interesting that you didn’t get the same result across seven SSDs. Since we’re on the same macOS version, are you also using an M6? I’m curious whether the hardware could make a difference, although I don’t know that it does.

Apple ran complete diagnostics on mine and said everything is running great. The engineer described my storage behavior as normal and said it involves a hidden mechanism to protect against disk corruption that isn’t listed under APFS snapshots. Disk Utility shows the space as purgeable on my Mac.

The supervisor said the reported usage may drop gradually over several days to a week, depending on how much data is on the drive. Someone I spoke with on Reddit reported similar behavior to mine, although theirs dropped by about 40 GB. I’d be interested to compare more reports from M6 users.

neuroanatomist wrote:

melvin3v wrote:

In my case, CleanMyMac ... System Data jumps to around 165GB whenever my external SSD is plugged in. As soon as I unplug it and reopen Storage settings, System Data drops back down to around 60GB.

As @etresoft points out, that's not supposed to happen. Period. If that's what you see on your Mac, then there is something very odd with your Mac. I would guess that BrickMyMac is part of the problem, for sure it's not part of the solution.

You state that plugging in an external SSD makes your System Data jump by over 100 GB. As a benchmark, on Golden Gate 27.0.1, my System Data has been between 150-160 GB. I use many external SSDs, and I have never seen System Data change when mounting or ejecting any of them. So I decided to mount more than one.

https://discussions.apple.com/content/attachment/659a1289-03e2-4924-be1a-706c767612e2

Top to bottom on the right of System Settings, that's my 2 TB internal drive, a small locally-saved disk image, five external SSDs (a mix of Samsung T7 and T9 1 TB and 2 TB drives), and for good measure an SD card in the MBP's internal slot (shows as an SD card icon) and another SD card in the slot on my Thunderbolt dock. With all of those drives/cards mounted, System Data is showing as 152.76 GB.

I then quit System Settings, ejected all the mounted drives (and unplugged/removed the 7 external ones), re-launched System Settings and clicked on Storage, and waited a few seconds for System Data to finish calculating.

https://discussions.apple.com/content/attachment/5e65633b-75ce-4373-aa87-9e3231dfe2bf

No change. Well, technically it went from 152.76 GB to 152.77 GB. It's definitely not >100 GB smaller after ejecting all the external storage media.

That's a great experiment and result, neuroanatomist. It shows that connecting and disconnecting external drives does not change System Data accounting by the Mac's Storage Tool. The user who was seeing this probably has installed things or made other configuration changes that have disrupted normal macOS operations. I agree with you that CleanMyMac is a prime suspect but I think other things could be installed as well.

My Mac is all good nothing corrupted Apple engineers just went thru and ran diagnostics and even had me send them clean my Mac screenshots 👍 If people do use clean my Mac just have to be smart and know what the heck your deleting and research. Where people get in trouble is if they go digging and delete files they shouldn’t have.