If you ever decide to change which drive your MacOSX Time machine backups are stored on, you may find that you will need to remove the “Backups.backupdb” folder from the old drive after you have performed the switchover.
Whilst you can do this in the conventional manner by right-clicking and selecting “Move to Trash”, you will soon discover that it is a very slow process. If you are confident with the command line you can perform the same action from the command line, using the “Terminal” application. I will reiterate that if you are not comfortable using the Terminal then this article may not be for you – a lot of damage can be caused by using the terminal incorrectly.
In order to achieve this you need to know where your Backups.backupdb folder is. With my setup the old folder is stored on an external drive called “LaCie1000”.
Using the Terminal
1. Go to the spotlight tool on your mac (the Magnifying glass icon) and start typing Terminal.
2. You should see a black icon and the application “Terminal” – click on this to launch the application.
3. If you do not know what your drive is called you can run this command:
Listing MacOSX Drive volumes in the command line
4. If you try and remove the folders using the normal “rm” command you might be presented with thousands of “Operation not permitted” errors. To get around this we can prefix our command using a “bypass” helper which will stop this error from occurring and thus successfully removing the folder. Apple, for whatever reason have changed the location of this helper so take note of the paths below, and choose the correct one for your operating system version.
In 10.8 Mountain Lion, bypass moved into ‘Helpers’:
In 10.10 Yosemite, bypass moved here:
Running the command
5. As I use OSX Yosemite the latter path is the one for me, and this will make my final command as follows:
sudo /System/Library/Extensions/TMSafetyNet.kext/Contents/MacOS/bypass rm -rfv /Volumes/[your disk]/Backups.backupdb/[path]
If you run the above you should start seeing a long list of files being removed.
It is important to note that this process is still not instant, but is far quicker in my opinion than the “Move to trash” method.