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Where Did All the Hard Drive Space On My Mac Go?

written by: Donny Yankellow•edited by: Rebecca Scudder•updated: 10/15/2009

Recently a coworker had over 70 GB of hard drive space vanish off his hard drive. What happened to the space? Read on.

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    Where Did It Go?

    Recently a coworker had over 70 GB of hard drive space "vanish" off his hard drive. He had no idea where it went. Looking into the folders and the individual folder sizes with a "Get Info" command we decided the space did indeed vanish. His files amounted to a total that should have left 70 GB of space on his hard drive. Instead he had 2 GB left. Here are some steps and utilities I ran on the computer to help try and solve the problem. In the end, he reformatted the drive and started fresh. Hopefully, some of these tips will help you so you can avoid the reformat.

    1. First thing I did was post a help topic in Apple's discussion forum. That post got me started on many of the following steps.

    2. Some questions to answer: Is Boot Camp running with Windows installed? This could be the root of the problem. Was a drive partition attempt happening and failed. This could cause the drive space to vanish. In our case, the answers were no.

    3. Run general maintenance programs: Download and run Onyx or Yasu (make sure you download the correct version for your version of OS X). At the very least try Disk Utility. If you have some money you can purchase Alsoft's Disk Warrior. It could be a directory issue and Disk Warrior can fix that problem. Even if Disk Warrior cannot fix the problem, I highly recommend it. It is one of the best, if not the best, disk utility programs you can get for a Mac (in my opinion). It has gotten me out of several jams that would have resulted in reformatting my hard drive.

    4. Run a disk scanning program that can tell you what is on your drive and what is taking up the space. We started with WhatSize and OmniDiskSweeper. Both are free, but neither revealed the missing drive space. It was then suggested that we try an open source program called GrandPerspective. That did it! The missing space was revealed. Unfortunately, in our case it only said the missing space was filled with miscellaneous files. It could not tell us what the files were, and we could not figure out how to see and delete them. Even so, I would recommend trying GrandPerspective out. It did what the other programs could not.

    5. Of course, as a last resort you can reformat the drive and reinstall OSX (which is what we had to do). If you have to take this route make sure your files are backed up. You might want to back up your entire user folder and applications folder to an external hard drive. If you have a drive with enough space you can use a backup program like Carbon Copy Cloner or DejaVu (my preference) to make a backup and then use Migration Assistant to copy over your account, files, and settings (look for how to do this in a future article).

    Disappearing hard drive space is a nightmare and from what I found in my research, a more common problem than you would expect. The steps above did work for some people, but not us. Hopefully, it will help someone out there and help avoid the reformat.