hard drive filling up macOS Sequoia

Bachbeethovenbrahms wrote:

There's no apparent delays / beach balling or long times starting up or shutting down. Disk Utilities shows the drive completely full even though I keep deleting large files. I've notices that when I breakdown Genreal / Storage, my Mail size keeps increasing. it was 9GB, now 10GB.

then, when I select the option to send files / messages / photos to iCloud, wouldn't that remove them from my local hard drive? That seemed to be working until I upgraded my OS. I'm now getting errors like "Mail cannot save information about your mailboxes because there isn't enough space in your home folder."

If the computer were really Totally Full it would exhibit

1 - unusual behaviours like constant Beach Balling

2 - issues saving changes to personal files

3 - unusually long time to start up or shut down

What is “Other” storage on a Mac, and how… - Apple Community

As for a " You'll need to download a 3rd party storage management tool " thank you @etresoft for that suggestion

To skip any more Q&A sessions, just download the Application Etrecheck directly from the Developer. 

It’s a diagnostic tool that doesn’t change your computer at all. It gives you a clear and easy-to-read list of both your hardware and software. 

You can get it for free or pay for extra features. And don’t worry, the report won’t reveal any personal information. 

Once you’re done, just copy and paste the full report using the Additional Text Icon.

From another contributor @etresoft regarding Free Space and Available Space 

Free vs available disk space huge differe… - Apple Community

Quote >>  “ The "available" storage is the amount of used storage that the operating system could automatically delete if it felt that it was really necessary. The "free" storage is the amount that you can actually use for something.

There are system processes that run in the background and automatically delete some of the "available" storage and convert it to "free". If you completely run out of storage, then those system processes will try a little harder. When you "delete" files you are just hinting to the operating system that you don't need those files anymore. The operating system will eventually remove them, but on its own schedule.

Certain tools will allow you to force the issue and manually clean up some of this storage and manually delete local snapshots. But that is only temporary. "  << End Quote 

Bachbeethovenbrahms wrote:

My iMAC hard drive keeps filling up after upgrading my ios to Sequoia 15.3. I've started using Microsoft Outlook for email but I don't understand the cause the excessive storage on the drive

Does the computer exhibit unusual behaviours like constant Beach Balling ?

Does the computer exhibit issues saving changes to personal files ?

Does the computer take an unusually long time to start up or shut down ?

To get a more accurate view of Used versus Free space

Use Disk Utilities

What about the other three questions ?

In case they were overlooked, which can happen and happens to myself from time to time

Does the computer exhibit unusual behaviours like constant Beach Balling ?

Does the computer exhibit issues saving changes to personal files ?

Does the computer take an unusually long time to start up or shut down ?

Bachbeethovenbrahms wrote:

Thanks for the response. yes - this is a Mac Mini. I've deleted gigs of storage (apps no longer needed, large videos on messages,...). have set up that Photos and messages move to my iCloud account where I've 1TB of storage , and then the next day my hard drive is full again.

Just to put a notion aside

iCloud is Only a Conduit to have files on iCloud so other devices you own and use the same Apple Acount can access the same files

iCloud is not like an External Drive where you can Archive files you not longer what or need on the Internal Drive

Bachbeethovenbrahms wrote:

I've deleted gigs of storage (apps no longer needed, large videos on messages,...).

That's part of the problem. If you're spending your time deleting scraps like apps and videos in messages, you're totally wasting your time.

Instead, you need to find out why you are running out of storage and fix that problem. Plus, it sounds like your hard drive is totally full, which is going to seriously complicate things. You'll need to download a 3rd party storage management tool. That will show you where your storage is being used. Hopefully, with that information, you can track down the culprit. It is absolutely impossible for anyone to tell you what is causing the problem. Anyone who tells you what the cause is with any confidence is wrong. There are just so many junk apps out there that run 24/7, creating massive files in hidden directories. You can't find this data in the Finder, in any Apple tool, or with a search. You must use a dedicated storage management tool and those are all 3rd party tools.

And to make matters worse, you can't actually delete any files. Only Apple has privileges to delete files. The best you can do is ask. Then, within a day or two, Apple will delete those files. But if your hard drive is already totally full, which it sounds like it is, or you have some out-of-control scam app, which it sounds like you do, then you're going to have a hard time getting in front of the problem.

have set up that Photos and messages move to my iCloud account where I've 1TB of storage , and then the next day my hard drive is full again.

iCloud is a file sync service. It really isn't a backup. If your computer is really going off the rails, and it sure sounds like it is, then iCloud is only going to make life more difficult. iCloud can effectively help you manage your storage and reduce your on-disk storage requirements, but only on a stable computer that already has a good amount of free storage. Alas, you can't go back now. If you try to turn iCloud off now you'll only make your life so much worse.

Bachbeethovenbrahms wrote:

I did just delete Garage band and its data and saved 3 GB, within 5 minutes, my Messages size under General-Storage jumped up from 7.12GB to 10.12GB and filled the space and I got the Mail 'out-of-space' message again and it shut down. (I took photos of the storage sizes just to watch what might have changed)

An aside to the Central Issue

To get the replies to your question in chronological order by Date 

Click on your User Name  >> Bachbeethovenbrahms   >> " Edit Profile and Preferences "

Scroll way down and look for >> >> " Other Preferences "

Change the >> >> " Default thread sort " to Oldest 

Add On

Just to clarify matters.

You mentioned in you text " iMAC" versus your user byline >> " Mac mini, macOS 15.3 "