How to install Mountain Lion on a disk that cannot be formatted in recovery mode?
Solution 1:
You should be able to use dd to destroy the partition's header. You can then format (erase) it and run the install.
From the installer run Terminal and type the following:
dd if=/dev/zero of=/dev/disk0s2 bs=1024 count=1024
Do be warned, this will irrecoverably destroy all data on that partition. But it looks like that's what you're expecting. Make sure you don't accidentally target the wrong thing.
Also note that I haven't done this, exactly. I've used this technique to destroy the entire partition table, not just a single partition. But I think it should work.
When you're done quit Terminal and run Disk Utility. You won't get any complaints about Core Storage.
Solution 2:
When the Partition tab of Disk Utility in Mountain Lion can not manage a partition on a physical disk that uses Apple Core Storage:
Ignore the Partition tab
Instead of selecting the logical volume group (to the left):
- select the encrypted logical partition (to the right of, and below, the LVG)
- use the Erase tab.
What techniques for disk, volume and file system management are possible with OS X, but troublesome within Disk Utility?
In particular:
- a physical disk may be invisible.
Solution 3:
Without destroying all partitions/slices of the physical disk:
Use the coreStorage verb of diskutil
To delete the logical volume group that is no longer required:
- get the UUID of the group
- run a command based on the following format:
diskutil coreStorage delete lvgUUID
If a logical volume within the group is mounted, it may be necessary to unmount before attempting destruction. Also maybe necessary to use sudo … sorry I can't be more specific, it's a couple of weeks or so since I last performed an action of this type .