System data taking up 115GB

Hey again! So following those instructions, Finder should show the size of both files and folders, which could then be sorted from largest to smallest.

Since that didn’t work for you, and considering your reply to me, if there are no other Users on your Mac, check these locations:

Open Finder.

On the top menu select Go.

While holding Option on the keyboard select “Library” under the Go menu, (Its hidden by default).

In the ~/Library, select each of these folders, then press Command I (i as in info). On the top right of the resulting window, it will show the size of the folder, we are looking for folders of large size:

Of the folders, check:

Application Support

Caches

Containers

Group Containers

Logs

Mail

Messages

Mobile Documents

Screen Recordings (If there)

Not all folders are just expendable, but store data or have some essential function for the OS or some other program you have.

If you find a large sized folder above, check:

~/Application Support/MobileSync/Backups, (These are iOS backups, perhaps you have old ones you don’t need anymore and can remove).

~/Caches, (If this folder is large, you can safely delete all the contents, although initially it may slow things down, they will build up again as you use your Mac, but you will not lose any data).

~/Containers/com.apple.mail, (Or Mail), (If this folder is very large, most likely you have Mail logging enabled, and if it’s Mail logs using all your space, you can safely delete them and disable Mail logging to prevent this in the future):

Open the Mail app, On the top menu, select Window > Connection Doctor > Show Logs, once that Finder window opens, hit Command i again to get the size, of it is large, delete all the contents and empty the Trash.

You can then disable Mail logging in the Connection Doctor window by unchecking it.

~/Group Containers, (I’ve found this folder to hold important data, such as Office documents and more third party data, and some local data, if you find this folder to be larger than it should be, let me know).

~/Logs, (These are typically just diagnostic logs and can also be deleted if using too much storage).

~/Mail, (This folder does hold copies of all of your Mail, so is important, all though you may have an IMAP account, and they are safely stored on the server, your Mailboxes “On My Mac” are also here, so also wouldn’t want to delete them without that backup and/ or exporting them first. I have seen certain email providers cause a glitch to where the Mail folder just grows and grows, so you can monitor this folder to see if that’s the case.

~/Messages, (If you use the Messages app, they are stored here). If you don’t need all the Messages on your phone etc. to also be on your Mac, you can delete the contents of this folder. (Make sure if you’re using iCloud for Messages that you disable it on your Mac first so your other devices aren’t affected).

~/Screen Recordings. I’ve seen this folder blow up due to third party applications such as video conferencing programs that maybe set to automatically download a copy of every session, so if you don’t need, can delete.

Empty the Trash after each deletion to see the results, although sometimes the Mac needs to be restarted to empty the trash at all, or to see the results.

Otherwise, if you can account for all the data, sometimes keeping data stored on an external hard drive is the best way to go. They are fairly cheap especially ones that are large in size. You can store data like your Photos Library and even iTunes Music Library on the external drive, make that the default, and delete the original Libraries, which may come in handy.

The new interface in About This Mac > Storage > Manage is really much better than it was and can usually deal with what you need or provide recommendations, but if you’re still having troubles, hope something here helps!!

In Disk Utility: Highlight the "Macintosh HD" further up and go to View and Show APFS Snapshots. If there are snapshots created, they will grow in size based on the amount of data you deleted. Snapshots in macOS are of the entire User/Apps volume. Snapshots are accounted for in the System Data storage space. They can be VERY large.

The snapshot listed on the left sidebar is a snapshot of the read only System volume and it's signed and sealed by Apple and macOS boots from this special snapshot. This makes the base OS immutable and completely unchangable by anyone except Apple. This snapshot has nothing to do with the snapshots used by you as the user. Time Machine will create snapshots but there might be other snapshots.

Other Storage:

Hey there!

The About This Mac > Storage > Manage Storage window has a great and easy way to see what’s using your storage.

This article may help:

See used and available storage space on your Mac

If you seem to have more Other/System storage than you should, (And this amount may vary depending on how you use your Mac), and you’ve already followed the above mentioned article, try these steps:

Open Finder, (The happy face icon).

On the top menu, click on View > As > List.

Next again click View > Show View Options.

From there, make sure these options are checked:

Always open in List View

Browse in List View

Size

Calculate All Sizes

Next, while still in the finder window, on the top menu, click:

Go > Home.

Right after, on the keyboard, press Shift Command Period.

(This will show any hidden files/folders that don’t normally need to be seen).

Afterwards, you should be able to see and find the files and folders using the most space. If much of this storage is in the ~/Library, which is the normally hidden folder in your Home folder, open it up and let me know what folder is the culprit. (On a side note, you can click on "Size" on the top column of the Finder window to sort by high/low etc.).

Otherwise, you may or may not have other Users on your Mac, you can check this also in Finder > Go > Computer > Macintosh HD > Users.

You may even have deleted users in there using space. And of course you’d want to empty the trash to complete reclaiming the storage.

Another possibility is that you have an extra partition or volume on your hard drive, perhaps after transferring data or reinstalling the OS.

You can open Finder > Go > Utilities > Disk Utility.

From there a screen shot or description may help.

Let me know how it goes, happy to help out if I can!

You actually went to the root library, you want the user library:

In Finder, click Go on the top, then, while holding Option on the keyboard, you should see Library about half way down the list.

Otherwise, in Finder, you can click Go > Home. While there press Shift Command Period on the keyboard to unhide the files. You’ll see the greyed out Library folder you can open. To hide the files again, you can use the same keyboard combo.

Cheers.

The system data used to be called "Other Category" and is a potpourri of files which can include:

• System temporary files

• macOS system folders

• Archives and disk images (.zip, .iso, etc. - often found in the Downloads folder)

• Personal user data

• Files from the user’s library (Application Support, iCloud files, screensavers, etc.)

• Cache files: browser, Mail

• Mail messages & attachments

• Fonts, plugins, extensions

• Safari reading list

• iTunes backups

• Crud resulting from jailbreaking your iDevice

• Game data

• Saved data files

• Call history

• Notes

• Media

• Voice memos

• Other files that are not recognized by a Spotlight search

• Media files that cannot be classified by Spotlight as a media file because they are located inside of a package

• Files created and modified by other user accounts on your Mac.

They can be located anywhere on your hard drive.

The files that you have control over are located in the Documents, Downloads, Pictures, Music and Movies folders.  You can use this free app, GrandPerspective, to find the largest files on your drive so you can determine if they can be deleted or moved to an external HD for storage.

Note: you can empty the Downloads folder after the apps and/or updates that were downloaded have been installed or applied.  Some users have found a couple of Gigabytes of files in their Downloads folder which are no longer needed. 

If you are not using Time Machine and you see Time Machine snapshots, then YES! Highlight them and Click the minus button to delete them. You can see the Private Size and Size columns showing the sizes of a snapshot.

Generally, the files in the System storage can be anything that cannot be categorized into app, movie, picture, music or document, such as:

1. Essential macOS operating system files;

2. Time Machine snapshot backups;

3. System log files and cache;

4. Cache from Browsers, Mail, photos and the third-party apps;

5. Old macOS updates;

6. Trash data and junk files.

Sometimes your Mac builds up an unnecessary amount of System files due to a bug, but most of the time it’s a normal part of how the operating system works. However, you can follow the below methods to manually reduce system storage on your Mac:

1. Empty Trash

2. Manage Time Machine Backup Snapshots

3. Optimize your Storage

4. Remove iOS Backups

5. Delete Cache Files

6. Update macOS

Hope it helps!

A third way to get to the user Library is to open Finder.

On the top menu select Go > Go To Folder, type this then press Return/Enter:

~/Library

This will also take you to the directory of your home folder’s Library.

Anyhow, hope you work it out, over 100 gb allocated to System Storage isn’t the most I’ve seen, but if you’re dealing with a 250 gb hard drive, that’s a huge chunk of it.