Some time ago I split the hard drive (500gb) in two partitions (250 each), now I have first successfully erased one partition but I still have the second one (Mac HD 2, which runs Mavericks) but I can not deactivate to erase it.

Anytime I try to remove it or deactivate it, this is the message:

"Deactivation failed, make sure that all the files and applications are closed"

Disk Utility Dialog

I am working on an other Hard Disk SSD 250 gigabyte which runs Yosemite, and I want to use the other 2 partitions for storage.

I assume that I am still using some applications and files coming from that partition and that's why I cannot proceed with the erase?

What you recommend for me to in this case? Deleting all the applications manually in the Hard Disk to make sure I am not running any of them? Is there any way to check which application(s) or file(s) are in use which causes the problem?

  • If you type lsof /Volumes/Mac\ HD\ 2 into Terminal, what do you get? Commented Jun 1, 2015 at 19:54
  • that's what i get "GitHub 336 tommasovilla txt REG 1,6 113232 26655239 /Volumes/Mac HD 2/Applications/GitHub.app/Contents/Library/LoginItems/GitHub Conduit.app/Contents/MacOS/GitHub Conduit GitHub 336 tommasovilla txt REG 1,6 88544 26655195 /Volumes/Mac HD 2/Applications/GitHub.app/Contents/Library/LoginItems/GitHub Conduit.app/Contents/Frameworks/LlamaKit.framework/Versions/A/LlamaKit GitHub 336 tommasovilla txt REG 1,6 390768 26655235 /Volumes/Mac HD"
    – Koala7
    Commented Jun 1, 2015 at 20:03

1 Answer 1


By typing the command lsof /Volumes/Mac\ HD\ 2 into the terminal, you can get a list of which apps are using that volume. The output looks like this:

enter image description here

The COMMAND column should tell you what's using your disk, and what you have to quit.

Based on your comment, it looks like the GitHub application is using your disk. Try quitting it first, then you should be able to do it.

In general, you can also use Recovery HD to safely perform disk operations without having open files spoil the fun. It has Disk Utility and you can eject the partitions that normally run OS X and have your way with them.

  • I would even recommend internet Recovery. This is because the HD would not be in use at all. Only the RAM will.
    – iProgram
    Commented Jun 1, 2015 at 21:32
  • It really depends on the situation. Using the solution I showed in the comments is faster and more convenient than having to restart into any form of recovery. Commented Jun 1, 2015 at 21:40

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