Today I got a new hard drive, and I wanted to do a backup of my laptop with it using Time Machine. Before the backup, I was prompted if I wanted to encrypt the backup as well. Well, I thought, why not?
Big mistake! The backup started, finished… and then Time Machine started to encrypt the backup drive. The ENTIRE drive. I was stuck at 1% for about 20 minutes when I got worried.
I couldn’t eject the backup drive, I couldn’t stop the encryption. I thought I was screwed.
I started looking on the internet for a way to stop or revert the process. One post claimed that it can take days to fully encrypt a drive. DAYS! I had been planning to take the laptop to a cafe just about right then. Guess that was not an option any more.
So long story short, lots of people claimed that an encryption in progress can’t be canceled. Others said it could. Some people said to use Disk Util to decrypt. But I found no option do do this while the backup was still running.
I finally got the following command for the terminal from some site, and tried it:
diskutil cs revert /Volumes/my_drive_name -passphrase
where you can get the actual value for your disk (the ‘my_drive_name) using this command:
ls -al /Volumes
I entered this command while Time Machine was still encrypting. The terminal asked me for my encryption password. After that, it only took a moment, and the disk started to quiet down a bit. I checked the status of Time Machine, and it said nothing more about any encryption going on. The Terminal said that the decryption was going on. And this is important: Decryption is not instantaneous. Basically, the terminal was now reverting all the encryping that Time Machine had started.
After a couple of minutes more, the disk slowed down and then stopped spinning completely. I ejected it, and it worked. I reconnected it then, and checked the Time Machine settings. The checkmark for ‘encryption’ was off! All looked well. So as a last test, I looked at the disk in Finder, and all the backup data was still there! So I guess this solved it, saving me maybe days of worry!