I have been facing an issue regarding a OS X Lion installation in my Macbook Pro 13. I used to have OS X Lion, then I decided to update my O.S to the OS X Mavericks; the update was pretty good, it was successful.
The problem was when I tried to "format" my Mac, during the re-installation of the O.S, a message appeared in my screen saying that the "Recovery partition could not be created", that was weird for me, I am not very good with my Mac yet, so I tried using a OS X Lion installer (which is in a CD), I tried to install from the CD (what many people call a "clean installation") but I got the same result regarding the "partition recovery".
I saw that some of the people mention that it is needed to delete all the partitions created, but in my case, every time I try to delete any of the partitions, it says "cannot unmount disk", and I am not able to perform any deletion over the partitions as mentioned in many tutorials.
So far, I noticed that a yellow alert appears in one of the partitions before pick a drive for the installation:
Additionally, this is what I have when I open disk utility:
I tried deleting the partitions using the disk utility and even using the Terminal commands (with sudo) but I always get the same error: The disk cannot be unmounted.
Please if somebody could help me, I will really appreciate, I've been without my Mac for more than 3 weeks. Thanks in advance.
Best Answer
When you're booted from the CD and looking at Disk Utility, you need to use the Erase tab, not the Partition tab. The EFI and Recovery partitions are hidden from view, so even if you delete all the partitions on the disk, it still won't delete that one.
If that still doesn't work, then you can open up a terminal window, and issue the following command:
That will zero out your entire hard drive, including all your partition tables. But it could take 2-3 hours depending how fast your hard drive is. Once it's done, you can create a new partition and install the OS.
If course, if you're really pedantic like me, you'd remove all media from the optical drive and USB ports, zero the hard drive, power off, zap the PRAM, reset the SMC, and then boot from Internet Recovery to do the OS install. That's factory fresh right there, my friend. The only thing it won't have after all that is the new computer smell.