Startup disk full, but full of what?

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Level 1

19 points

Startup disk full, but full of what?

I keep getting the message “Your startup disk is almost full” on my 2014 MacBook Pro (120 GB storage, El Capitan 10.11.6), and I can’t seem to figure out what’s filling it up. The storage bar (which I don’t totally trust) shows that most of the space falls under “Other”. When I use “Get Info” in Finder to account for the space, I find large chunks unaccounted for. For example, 118 GB is filled on the drive as a whole, but when I add up the individual components listed (Applications, Library, Users, etc.), I only get 103 GB. As another example, the space taken up under my username is 66 GB, but when I add up the parts (Applications, Documents, Pictures, etc.), I only get 47 GB. I’ve tried restarting, but this doesn’t clear up much space.

I have a feeling this is all related to the scientific computing work I do on my laptop, running a lot of resource-intensive programs in MATLAB. But if so, I’m not sure where all that data is stored and why it doesn’t clear automatically when I close MATLAB or restart the computer.

MacBook Pro with Retina display, OS X El Capitan (10.11.6), null

Posted on Jul 3, 2017 10:04 AM

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Answer 1

Tesserax

Level 10

161,644 points

Jul 3, 2017 11:50 AM in response to Tnedde

See if any of the following articles can help:

What the "other" space in About This Mac? - Apple Support
Free up storage space on your Mac - Apple Support
What is Other Storage on Mac OS X and How to Remove It? - igeeksblog.com
What the "Other" Storage Space in in Mac OS X & How to Clear It Up - OSXDaily

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Answer 2

BobHarris

Level 9

58,665 points

Jul 4, 2017 10:16 AM in response to Tnedde

Also see "What is 'Other' and What Can I Do About It?"

<https://discussions.apple.com/docs/DOC-5142>

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OmniDiskSweeper (free download)

<http://www.omnigroup.com/more>

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When using OmniDiskSweeper, or any utility that shows all your files... See the following article if you want to run it as root

<http://www.macobserver.com/tmo/article/how_to_recover_missing_hard_drive_space>

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Boiler Plate Warnings:

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If you have a recurring, running out of disk space, problem, then OmniDiskSweeper may help identify where the space is going. Posting the suspected locations and files will help the forum help you to figure it out. Remember, we cannot see into your disk, you have to give us information to work with.

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DO NOT delete files in your Home Folder -> Library tree as there are things like your iPhone backups, your email messages, your application preferences, etc… If you think you have found something in your Home Folder -> Library that can be deleted, you should ask first.

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DO NOT delete files outside your home folder, as you may end up deleting something essential to Mac OS X, and turn your Mac into an expensive “Door Stop”.

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I will point out that you will find some very large files in private -> var -> vm (these are the Mac OS X virtual memory paging files (swapfiles) and where Mac OS X stores the copy of RAM when your Mac is put to sleep). The swapfile(s) get deleted on reboot, and the sleep image is just going to be created again when you put your Mac to sleep.

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If you think you have found something to delete outside your home folder, it would be best to ask first before deleting. There are many examples of people deleting files outside their home folder, or renaming files, or changing the ownership or file permissions, and then their Mac stops running. Do not be one of those people. Ask first.

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Answer 3

Tnedde Author

Level 1

19 points

Jul 4, 2017 7:52 AM in response to Tesserax

Thanks; these articles have some useful suggestions about clearing up space and I will try them. But I was really hoping for an explanation for why the whole seems to be greater than the sum of its parts in Finder. Are there files that are hidden from view in Finder? Is the size information under "Get Info" unreliable? Or is there some other explanation?

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Answer 4

Tnedde Author

Level 1

19 points

Jul 4, 2017 8:23 AM in response to BobHarris

Thanks for the tip on OmniDiskSweeper. Upon using it, I immediately noticed a drive called “MobileBackups”, separate from my Mac hard drive. This drive supposedly has the same storage space as my Mac hard drive (120 GB), but seems to be even more full. It’s undoubtedly related to the Seagate external hard drive I have been using to back up my computer, although that drive is not currently connected. It has been causing me all kinds of headaches and will be replaced soon.

This leads to all kinds of additional questions. How would I even know this drive exists without OmniDiskSweeper? How can it be stored on, and yet not part of, my regular hard drive? Why is it invisible to a Spotlight search? How much of my 120 GB is it *actually* taking up (presumably with a backup of the hard drive itself!)?

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Answer 5

Tnedde Author

Level 1

19 points

Jul 4, 2017 10:18 AM in response to BobHarris

Thanks for the info, and I’ll wait for answers on some of my remaining questions.

The only local snapshot that appears in Time Machine was created less than a half hour ago, so that does not seem be the thing has been taking up all this missing space (reminder: at least 34 GB unaccounted for; see my original post).

I guess the most important question for now is, should I use OmniDiskSweeper to delete everything in the MobileBackups “drive”? When I sweep it, it claims this drive stores 77.8 GB; yet the total space occupied by Applications + Library + System + Documents + Pictures is over 80 GB (using Get Info). So obviously I don’t actually want to delete 77.8 GB from my 120 GB hard drive; I just want to delete the extraneous stuff.

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Answer 6

Tnedde Author

Level 1

19 points

Jul 4, 2017 2:08 PM in response to Tnedde

To answer one of my own questions: Yes, Finder hides some files and folders from you, and you can reveal them by entering the appropriate commands in Terminal. This has led me to discover 8 GB in downloaded emails, despite my (almost) never having used the Mail program!

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Answer 7

BobHarris

Level 9

58,665 points

Jul 5, 2017 2:55 PM in response to Tnedde

System

DO NOT delete anything in System. it is the operating system. Deleting things in System will be one of the things that turns your Mac into a "Brick"

Library

There are 3 Libraries.

/Library

/System/Library

/Users/<yourShortUsername>/Library

DO NOT touch anything in /System/Library, as it too is part of your operating system.

/Library is a global (as in all users on the system), and may have some things that are specific to an application, including some applications you want to keep using. It also contains things such as your network preferences, and some other settings that are system wide.

/Users/<yourShortUsername>/Library will be specific to your login. It will contain things like your email, your browsers bookmarks, your personal system preferences, and things the apps you run want to store that are specific to your use.

Applications

Some macOS installed apps cannot be removed, and a few even if you jigger the system so you can remove them, can break your system, as some apps depend on other apps being there.

Your own installed apps can be removed.

Documents + Pictures

These are yours. You can keep or delete them as you wish. Although if you use iPhoto or Photo, you should do the deleting inside the app so its metadata about your pictures is keep consistent.

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