Why is system data on my macbook pro over 300gb?

[David Taub]

I had over 250gb of free space on my internal 500gb hard drive. Suddenly it's down to about 80gb. When I check storage via 'about this mac' it shows me system data is using like 300gb. What is happening? Thanks for help.

I am on macOS Monterey 12.4
Macbook Pro mid 2015
2.5ghz Quad core intel i7.
16gb

 

[jav6454]

Is there any further breakdown?

 

[David Taub]

What would you like to know? For a long while my available space was about 250gb. This drop was sudden. I'm not sure when it happened, but now my disk shows 86gb left. My applications use most of the disk at around 60gb. All my work is on external drives. Here are some screen shots. System data was 298 earlier today. Now it's 261gb. When I hit 'manage' you can see there's no way I've got over 400gb of files on my hard drive.

I wonder where all those gb's are going?

 

[jav6454]

This is a new one for me. I went into the same settings to see if I could get more details on my Mac about "System Data", but there is no further breakdown.

I did however look thru some old posts and found that System Data is usually the following:

• Log files and/or cache
• Virtual Machine files
• Temporary files
• Runtime resources
• Data/files used by the system
• Old iOS back-ups
• Local Time Machine back-ups

You could try to clear out quick things like back-ups that were unintended. Mind you the downloads folder also counts in "System Data"

Do the following at your risk.

Clearing Cache Files
The system and applications you run on your Mac will create cache files in the Library Folder. To reclaim more space for your Mac, you can delete unneeded cache files manually.

1. Click the Go menu in Finder and select Go to Folder.
2. Paste the following file paths into the search box and click the Return key.

• ~/Library/Caches/
• Library/Caches/
• /System/Library/Caches/

1. Move unwanted files in these cache folders to the Trash.
2. Empty your Trash.

Delete Log Files on Mac​

Log files are a part of the System Data. You can delete them manually or automatically.

How to clear log files on Mac manually:

1. Click the Go menu in Finder and choose Go to Folder.
2. Paste ~/Library/Logs/ into the blank box and press the Return key.
3. Find the log files you want to delete, select them, and press Command + Backspace keys.
4. Continue to remove the log files in /Library/Logs/.

 

[James_C]

Given that the space has decreased relatively quickly and it has consumed a lot of space, my best guess would be that you have time machine enabled, and for whatever reason it was not able to access the normal Time Machine backup disk and has created a Local Time Machine Snapshot. You can remove these snapshots, if this is the case, by following Apple’s guide here https://support.apple.com/en-gb/HT204015.

I tend to use Daisy Disk to see what is actually taking space on my SSD. Might be worth investing in a copy if Time Machine Snapshots is not the answer. https://daisydiskapp.com/index.html

 

[David Taub]

Given that the space has decreased relatively quickly and it has consumed a lot of space, my best guess would be that you have time machine enabled, and for whatever reason it was not able to access the normal Time Machine backup disk and has created a Local Time Machine Snapshot. You can remove these snapshots, if this is the case, by following Apple’s guide here https://support.apple.com/en-gb/HT204015.

I tend to use Daisy Disk to see what is actually taking space on my SSD. Might be worth investing in a copy if Time Machine Snapshots is not the answer. https://daisydiskapp.com/index.html

Thanks, but I use Carbon Copy Cloner to backup my internal ssd to an external hard drive. I will take a look at that daisy disk app.

 

[David Taub]

Ok. I found it. I went into CCC that backs up my internal ssd. I found something called 'Snapshots' that was on automatically. It listed 168gb of use/data. This went back as far as March 2020. I cleared it all because I already have backups, full backups, to two external drives. And bam. I now have 260gb of free hard drive/ssd space again.

jav6454, james, thanks for your help...it got my brain thinking outside of the narrow space my own was working in...

 

[usagora]

Resurrecting this thread because I'm confused why Apple states, "your Mac will count the space used by snapshots as available storage", yet according to Disk Utility, that space is NOT available (otherwise it wouldn't have said you only had 86 GB left. Do they simply mean that once your drive get full beyond a certain level those snapshots will automatically be deleted as needed? If so, it would be nice if Disk Utility didn't include them as used space, which can cause users to panic that their disk is nearly full (like I just did when I discovered I have over 300GB of system data!).

 

[dragonfly1]

I also noticed that my M1 MacBook Pro had little space left (1TB SSD). Checked the Storage setting in Preferences and that indicated 315GB for System Data!?

I wonder if it has something to do with OneDrive. OneDrive has been an absolute nightmare (not syncing properly and showing "Processing changes" constantly).

Just also noticed that the Users folder size indicated in the finder is 9.66TB !!?!? How is that possible?

 

[smirking]

I also noticed that my M1 MacBook Pro had little space left (1 TB SSD). Checked the Storage setting in Preferences and that indicated 315 GB for System Data!?

Download Omni Disk Sweeper and let it compile a real time profile of your disk usage. Then use it to drill down into any folders that look unusually large in size. This can be time consuming, but you'll eventually find your culprit. I've found some pretty weird stuff that I totally forgot about.

The worst offender I found was over 200GB of mail log files. I had turned on connection attempt logging in OS X mail about a year before and had forgotten about it.

 

[jeffhalmos]

Download Omni Disk Sweeper and let it compile a real time profile of your disk usage. Then use it to drill down into any folders that look unusually large in size. This can be time consuming, but you'll eventually find your culprit. I've found some pretty weird stuff that I totally forgot about.

The worst offender I found was over 200GB of mail log files. I had turned on connection attempt logging in OS X mail about a year before and had forgotten about it.

OmniDiskSweeper was gold for me. Found stuff CleanMyMac and a few others couldn't. Thanks!