I put an SSD drive into my macbook pro. I should say that this drive hadn't been formatted and was a bootable drive with Yosemite OS on it, taken from another macbook pro... I booted the system up in restore mode and began the process of restoring from a time machine back, on an external plugged in via firewire 800 caddy. It said, "erasing drive", it asked me for a password, I wasn't sure why so typed my usual system password. I received the message, "drive could not be erased" Since then the SSD drive has only show up in disk utility, not on deskop or in finder, and it cannot be erased in disk utility. I gather from speaking with a few more enlightened apple people that it has been converted to a core storage drive... I will post up a couple of helpful terminal read out pictures. How do I get my SSD drive back?? Thanks in advance, Chris


diskutil cs

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    Yosemite + Core Storage is enough to make a grown man weep. Fixes start with 'discard everything & reformat..' not a happy procession
    – Tetsujin
    Oct 26, 2014 at 21:22

2 Answers 2


You can blow away a corestorage disk partition by booting in Single User Mode... then use this command:


dd if=/dev/zero of=/dev/disk0

After a moment you will see an error that the corestorage volume has come offline unexpectedly (that is because you have destroyed it). You can now type Ctrl+. to stop ruining the disk.

Then you can boot in Recovery mode (hold down Ctrl+R upon boot) and proceed to format this disk.


Much Better way to do this, you don't need to format at all, as the drive can be reverted. Apparently a lot of the commands relating to this are undocumented? I have no idea really but I had to go through the same process to get disk utilities to allow me to do anything related to partitioning.

Here https://support.symantec.com/en_US/article.HOWTO109622.html is step by step to removing corestorage designation.

Maybe to late for you, but anyone else with this problem should give this a try

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