Today I was trying to upgrade the OS X on my Mac mini via the AppStore which seems harmless and seamless like every other small OS X updates. Unluckily it turned into a nightmare (almost).
I was not paying attention to the details of the Update, it was something like Command Line Tools, Combined update and an update on the Recovery Partition. The install was smooth, after I restart the computer, it was stuck in a screen with a prohibited sign, like this one (this is taken from the internet):
I didn’t panic until I restart a few times and I keep getting this screen. I boot with the verbose mode and I see the message where it stopped is
still waiting for root device
I was not sure what’s going on, I have done clearing PRAM, using Disk Utility to fix permission, but still the problem persist.
Finally I solve the problem by recovering the Mac using my Time Machine backup to 30 mins ago which is on my USB external drive I always plugged in. It was the first time I used Time machine to perform full recovery. I immediately feel grateful that I decided to purchase this external hard drive and have it always plugged in.
The lesson of this story is, if you didn’t use Time machine to back up your computer, use it, backup often. You can thank me later 🙂