Windows boot issue with Yosemite (Windows on an external SSD)

Discussion in 'Mac Pro' started by HHarm, May 1, 2015.

  1. HHarm macrumors regular

    Mar 4, 2009
    I finally managed to move from 10.8 to 10.10 on my MP09. On my previous attempt I had some strange slowdowns that made me roll back to Mountain Lion.

    There's one problem that needs fixing. On 10.8 I had a configuration that allowed me to boot to Win8 without using Bootcamp or the boot screen. Here's how it worked....
    • OSX was on a 3 X Intel x-25 Raid0 array
    • Win8 was on an external SSD that was connected to an eSata port on an Accelsior_E2
    • I configured OSX so that the Windows SSD was the default boot drive. I would then toggle the OS that I wanted to boot from the powers switch of the external SSD enclosure (if the SSD's power was off the MP would boot to OSX)

    After installing Yosemite the setup won't work.
    • When I choose Win8 as the boot drive (from OSX) the boot fails with a black screen with an error message "No bootable device -- insert boot disk and press any key"
    • If I choose the boot drive manually (by pressing down option key) I can boot normally to Win8
    • Hardware-wise the difference to the old setup is that my OSX is now installed on the Accelsior

    Any idea what's the source of the problem and how to fix it?

    I'm planning to get a GTX980 or a Titan X and at that point I won't have access to the boot screen.
  2. stevedusa macrumors regular

    Jun 12, 2012
    I don't think you can boot to Windows an external storage device in this case.

    Your best bet is either add an internal storage and boot from there.
  3. IowaLynn macrumors 65816


    Feb 22, 2015
    We know Windows won't install to Thunderbolt attached drives but can be moved there and boot.

    Don't we also see some controllers as internal even if it has an "e" connector?

    And sometimes OS X could not be installed on early Sonnet Tempo Pro SSD controller but had to be cloned, or the drive moved to SATA II and back to get it to work.

    WinClone and Paragon HDM have been used on the 6,1 to move Windows off the internal drive to Thunderbolt.
  4. HHarm thread starter macrumors regular

    Mar 4, 2009
    Still strugling with the problem...... a few extra points:
    • The setup worked just fine with Mountain Lion (Win8 was bootable from eSata)
    • And I get the same error if the Win8 SSD is connected to an internal Sata connector. Again I can manually boot to Windows

    Did Yosemite change something in this area?

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