How to Wipe a Mac with a Bootcamp Partition

One of the boffins was recently let go. When his MacBook Pro was recovered from him, the other boffins perused the contents to make sure nothing was out of order. It was then my job to save any important data and then wipe the computer. This is what I did and what I learned that I should have done instead to wipe a Mac with a Bootcamp partition.

Saving the “Important” Data

I’m not really sure what constitutes “important” data, so I just figured I’d save any file that wasn’t part of the Mac OS X operating system or an application file. My plan was to make a folder on the Desktop and move any files that met that criteria into it. Afterwards I would move that folder off to some network storage.

My first mistake was trying to just copy and past from the “All My Files” area in Finder. “All My Files” only shows the file name; it doesn’t save the file location information when you move files from it to another folder. A lot of the files on this computer had the same name, so when I tried to put them into the same folder I was prompted to skip them, to stop the move, or to replace the files. I chose to replace the files until I realized that they probably weren’t identical.

Thankfully there was a Time Machine backup, to I restored the files from there and started over.

Lesson learned: When you’re saving a user’s data, just copy the entire home directory for the user. This will retain the file structure to prevent lost files.

After getting the files together, I tarred and 7-zipped the folder with a very useful tool called Keka. Then I uploaded it to a new file-sharing system that I implemented last week. I spent too much time figuring out why I couldn’t upload files larger than 2 GB. I changed the settings in the php.ini file to allow for larger uploads, but I had overlooked that there was also a .htaccess file limiting upload size.

Lesson learned: If you hit a file size limit, check php.ini and .htaccess.

Wiping the Mac

An easy way to wipe the data off of a Mac is to use the iCloud remote wipe feature. Just connect the computer to iCloud through System Preferences, then go to the iCloud website and tell iCloud that it has been lost. The funny thing is you can do this all from the computer you’re wiping. Just login to iCloud with your Apple ID, click “Find my iPhone” (this is the option for phones and computers), and a map pops up showing you where your computer is. Click on the device to wipe it. You will be prompted to enter a 4-digit PIN and a message. The computer will then shutdown or restart. The screen then shows a place to enter the PIN and the message your entered into iCloud. Enter your PIN, and the computer boots to the Recovery partition.

From the Recovery partition you can open the Disk Utility to securely erase the main partition and/or reinstall Mac OS X.

Dealing with Bootcamp

One factor that I didn’t account for was that this boffin had a Bootcamp partition. I saw it in the Finder when I was saving the data, so I got all the files, but when I booted into Recovery it showed two empty partitions instead of just one. I figured I could just reinstall the OS and then put the partitions back together with the Bootcamp Assistant.

I was wrong.

Because I had wiped the computer, all the Bootcamp information about the second partition was lost, so I couldn’t put the partitions back together with the Bootcamp Assistant.

Lesson learned: Use the Bootcamp Assistant to put the partitions back together before wiping the computer.

I couldn’t use the Bootcamp Assistant and I also couldn’t put the partitions back together in the Disk Utility because the hard drive could not be unmounted (it’s the same drive that the Recovery partition is on). So what I did was create an Ubuntu Live CD. I put the CD in the drive, restarted, and held the “c” key on the keyboard to boot from the CD drive.

If you’re doing this, be sure to choose the option for “Try Ubuntu” not “Install Ubuntu.”

When the Live environment loaded, I opened GParted from the System menu under Administration. I deleted the two main partitions (be careful not to delete the EFI boot partition or the Recovery partition), and then I created a new one. Ubuntu can’t format HFS or HFS+, but that’s not a big deal. I just left it as an unformatted partition.

I rebooted the computer. The Recovery menu loaded. I opened Disk Utility to erase and format the partition I just made. The firm deals with sensitive info, so I have to do a secure erase (7 passes, 10+ hours). After that’s done I’ll reinstall OS X and be on my way.