I'm planning to replace the optical drive in my MacBook Pro 9,1 (mid-2012, non-retina) with an SSD and make the two internal drives into a fusion drive, and I know that creating a boot camp partition on a Mac without an optical drive can be a challenge. So I want to create my boot camp partition before I create my fusion drive.

I couldn't find an answer to this in my googling. I know that you can create a Boot Camp partition if you already have a fusion drive.

Can I create a fusion drive using an HDD that already has a boot camp partition on it?

4 Answers 4


From my hands-on experience, I'd have to say, "negative".

I've created a couple of fusion drives on a 2008 Mac Pro from devices with preexisting partitions. Building the fusion in Core Storage destroyed all partitions on the media.

  • I've done it several times on a 2011 mbp so at least it may depend on your configuration. See the other answers.
    – xpereta
    Commented Mar 5, 2014 at 10:11

With trepidation, and after a full backup, I specified two arbitrary slices from two already-partitioned hard drives:

diskutil cs create <myTestVolumeName> disk0s2 disk1s4

Because I picked two partitions I could sacrifice, the HD partition (20GB) was quite small compared to the SSD partition (115GB) which isn't at all the normal use case, but added an extra wrinkle for testing.

To my surprise, and supporting what Bbh noted previously, it would seem you can specify slices for not just one, but both parameters.

I have a working ‘Fusion Drive’ and still have my other ‘stock’ partitions and recovery drives intact. I restored a system to the wee beastie to see if <myTestVolumeName> would boot my MBP5,4 (mid-2009)… It does; this bodes well.

So the answer AFAIK is Yes, as to preparing/preserving Boot Camp and exising partitions, at least on my setup. YMMV.


I just did this yesterday.

I was having difficulty with Bootcamp getting stuck at partitioning with my 2011 iMac with a DIY fusion 2TB+256GB. So, I disabled fusion, installed OS X on my HDD, ran Bootcamp and set up a partition for Windows on the HDD, installed Windows 8, booted from OS X thumb drive and then created a fusion drive with just the slices I wanted to use, leaving the recovery and Windows slices alone.

The Windows and recovery partitions are not visible at Option-boot until after I installed OS X again on the fusion drive.


I think you can. In creating the Logical Volume Group, I read of a fellow who preserved both his Bootcamp and Recovery partitions by the simple act of specifying the SLICE that contained most of the HDD data. Forexample,

Diskutil cs create yourdisk d1 d2s2 where d2 is the HDD that contains the major data at d2s2 and Boorcamp at d2s3 and the recovery partition at d2s4, or some similar setup.

  • A link to your source on that would be interesting. :) Commented Jan 29, 2013 at 3:42

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