I copied this from another thread I just posted in
I can confirm the listed configuration works without flaws on 2012 27inch iMac, no CD rom needed.
What you'll need:
LaCie Rugged SSD (comes with thunderbolt cable)
Copy of windows 7
Winclone 3
I found this thread while searching for a solution for my installation problems.
In the meantime i solved them with a "personal" solution, made up with different bits of documentation i found online.
If somebody else will find this thread in the future, here is what i found:
First, here is my configuration - MBP early 2011, with 8Gb RAM, 128Gb Apple SSD, and a 500GB 7200rpm drive mounted in place of the original SuperDrive (which now resides in an external USB enclosure). When i purchased the computer second hand, i erased the original installation, and reinstalled Mountain Lion 10.8.3, merging the two disks in a Fusion volume.
Unfortunately the performance of USB 2.0 disks is good only for Time Machine and movies/music backups, as there is no USB 3.0.
That's why i bought a Seagate GoFlex 1Tb Thunderbolt drive (which has the added advantage of being easily used as a Thunderbolt interface for multiple 2.5" HDs).
The idea was to use it for a separate Windows installation.
Here is a short resume of the hurdles i found in the process.
BootCamp utility creates a new partition at the end of the tradition (spinning) HD, but i had to edit the plist to get the option of preparing a USB thumb drive for Windows 7 or 8 installation.
Mountain Lion and Lion plist's are different, be aware! You'll find the instruction for Mountain Lion on the Web, with some patience.
I found that both Windows 7 and Windows 8 don't allow you to install the OS on the BOOTCAMP partition, no matter how hard you try (formatting, as per instruction; erasing and re-creating the partition; etc).
Of course i could not install directly to the Thunderbolt drive, either.
No matter how the drive was partitioned (GPT, MBR; FAT32, NTFS).
The only option left was to prepare the Thunderbolt drive using "imagex.exe" Microsoft utility, and the "install.wim" available on the installation Windows DVD or ISO image, using either a real Windows PC, or a Windows x64 virtual machine.
You'll find the guide on the Web with a simple search.
Unfortunately i have Vmware Fusion, which does NOT allow you to connect a Thunderbolt drive to the virtual machine! So i had to prepare a slow USB 2.0 drive...
I had in mind to do the installation using the USB 2.0 disk, and clone the resulting installation to the Thunderbolt drive using WinClone.
No success! :-(
I tried with Windows 7 and Windows 8, in both instances the screen went black after some time, and the installation couldn't be completed.
I thought i had found a dead end...
Then i realized that there could be some problem related to the nature (and slow-ness) of the USB drive.
So i prepared the USB drive once more, and did a "sector-by-sector" transfer from the "prepared" disk to the Thunderbolt one, using the "dd" utility from Terminal.
After that, i rebooted using the Thunderbolt drive, and the installation started... but the screen didn't do black after some time, and everything went fine (rebooting twice with "option" to proceed with the installation).
Now i have a working Windows 7 copy on my Thunderbolt drive. The only peculiarity is that, using the virtual machine method, the destination disk is partitioned with a small FAT32 boot partition (mine is 350Mb), and a larger NTFS partition with the Windows installation.
A side note: as i "mirrored" the USB 500Gb 2.0 disk to the 1Tb Thunderbolt using dd, with no advanced arguments, the resulting partitions occupied only 50% of the 1Tb disk...
No problem, it's possible to resize the NTFS partition with the Windows files, to use all the available space.
I even dare to do it while booted in Windows 7, using Computer Management > Disk Management.
Everything was fine when i booted in OSX, and booted again in Windows 7!
After all my efforts, and many hours of experiments with Win 7 and Win 8 installations (dd took many hours, cause i used /dev/disk instead of /dev/rdisk, my bad!), i found WHY the installation from WINSTALL usb drive didn't allow to choose the BOOTCAMP partition.
THERE IS SOME PROBLEM WITH TUXERA NTFS!
A friend tried the same default procedure recommended by Apple (BootCamp .pdf guide), and found the same rodblock: the BOOTCAMP partition could not be used for installation!
It was evident that the problem was not related to the peculiarities of Fusion drives.
We had the same idea: maybe it's Tuxera NTFS!
After disabling Tuxera (in System Preferences), before partitioning the disk with BootCamp utility, we gave a go to the Win 7 installation, once more.
No failure, everything works as it should!
You have just to format the BOOTCAMP partition, as per Apple instructions.
Sorry for the verbosity, but i hope i have been clear enough, so that the uninitiated could find the missing bits of infos with Google, using the right words in their searches.
EDIT:
i posted an enquiry on the MBP sub-forum, but i had no reply.
Then i found this thread.
I thought that it was more meaningful to post a follow-up on the iMac sub-forum (because it has to do with Fusion drives... in my MBP it's a post-sale hacking), to add my experience to other informations that were already given.
cheers
CJ