Boot Windows 7/8 from GPT on BIOS system : No hybrid MBRs or DUET!

Thank you. I will have to set aside some time to try this. I kinda thought the same, but wondered if someone else may have hit this already.

Yes I suspect this will take a couple of hours to complete. Since your original drive is 3TB, I would try the dual boot scenario by creating 120 GBs of free space on it next to your Win 7 install. By dual booting this way you can try out Win 10 without risk of loosing a program that may only work with Win 7 (for instance Core Temp doesn't always play nice with Win 10). One other potential little snafu might be fixing the BOOTmgr and BCD on the USB stick. Generally, MS Bootmgr files are NOT forward compatible, but they are all backwards compatible. For instance; a Win 7 BOOTmgr will not boot Win 8, 10, but a Win 10 Bootmgr will boot Win 10, 8, 7, Vista. You may need to copy the updated Win 10 BOOTmgr to the USB stick (simple to do). Just rename the Win 7 BOOTmgr file and copy over the Win 10 BOOTmgr to the USB stick. Everything should boot fine then.
If you try this, let us know how you make out. Although it's a bit of work, I'm confident this should work, but confirmation of it might help out some others in a similar situation.

My windows partition is 198GB, then I have a 500GB and 2TB partition on 3TB drive. I have used Macrium to clone the windows partition onto a old 160GB drive (took some trickery to create a small partition ahead of the main drive to keep Macrium from changing the disk type to GPT and keep MBR).

Now I am trying to fix the booting off the newly cloned drive. Tried to use my Windows 10 USB key to do the repair, but on boot it says /boot/bcd is messed up and I need to repair. I have run the repair more than 3 times. I think I need to make a Win 7 USB key and fix it using that.

Have you tried using EasyBCD to fix the 160GB 'ghost' HDD with Win 7 on it so you can boot up the computer with it? It works great on MBR systems, not so good with UEFI, but they're working on it.
There are a number of good HDD partitioning utilities out there. I like Aomei PM because it will change a disk from GPT to MBR
and vs versa without loosing any data. I'm willing to try to help you get this done, so let us know how you're progressing.

Actually you should be able to add the Win 7 on the 160 GB 'ghost' HDD to the boot menu of the USB stick you've been using to boot your GPT disk. EasyBCD is an easy way to do that. You can use EasyBCD to not only edit the system BCD store, but any other BCD store on the computer. Go to File> Select BCD Store> browse to the partition with the other BCD on it.
Start the computer the normal way with your original GPT disk using the USB stick. Plug in the 160 GB 'ghost' HDD - make sure it shows up in My Computer (Windows Explorer). Start EasyBCD. If it doesn't automatically load the system BCD on the USB stick, go to File> Select BCD Store> browse to the BCD on the USB stick and load it. Go to Add New Entry. Under Type select Windows Vista/7/8. Under Name type in something unique so you know it's for the 160GB HDD. Under Drive select the partition (or drive) from the drop down where the Win 7 on the 160 GB HDD is located. Click Add Entry. You should see Saved Successfully at the bottom. Shut down the computer. Remove the original GPT disk. Install the 160 GB 'ghost' HDD. Start the computer with the BCD on the USB stick which now has an entry that points to the 160GB HDD. Once the computer is started up using the 160 GB HDD, you can use Easy BCD to fix the MBR and BCD on it so you can boot it up without the USB stick.

So, an update. I am running currently on Win10, it successfully upgraded once I fixed the boot issues on the "temp" older drive. I can see my Win 7 partition, but I have no real need to keep it around. I made a backup using Macrium before I started this, so I can revert back if really needed, but things are running well.

I ended up getting it to book from the temp drive by using my win7 boot CD. The repair option didn't work no mater how many times I ran it, but by running bcdboot.exe and forcing new boot files it then booted just fine. After that the win 10 upgrade went by without a hitch.

Now to using Macrium to move it back to my first parition of the GPT 3TB drive,and update my USB key to use the Win10 boot loader (basically running the steps from this thread one more time).

Will post once this is all done. Thanks for the push to do this... I was thinking of just sticking with 7 as this is my plex server.

Thanks PHubb, I am up and running again with 1 drive (GPT) using and updated win 10 image boot USB.

One instruction which I found I needed when running the first post on windows 10, is that I needed to set the device and osdevice attributes of the boot menu with the following commands:

bcdedit /store d:/boot/bcd /set {default} device partition=c:
bcdedit /store d:/boot/bcd /set {default} osdevice partition=c:

where d: is the USB key.

I swear I didn't do this for the original win7 boot a month ago, but now with windows 10 both were showing up as "unknown" via bcdedit and windows wouldn't boot, showing an error that it couldn't find /windows/system32/winload.exe.

After that command all is good.

1st: I'm glad you stuck with it and had success.
Yeah BCDEdit is a better and more functional tool, but most stay away because it's command line.
As you found out, setting the store and partition path works.
Another tool I completely forgot to mention is the built-in Windows tool called bcdboot which allows one to type simple commands to set an OS store. For instance: bcdboot [drive/partition]\windows and it will automatically fill in all the other data necessary to boot the OS on that drive/partition.

I admit that this was a bit involved as a work around/strategy to solve your problem, but I'm wondering if others will come up with something simpler and easier in order to accomplish the same thing.


I'm also interested in knowing what you think of Win 10. I have it on a drive/partition, but haven't gotten into the habit of using it yet. I use my PC for work so I need Win 7 stability and zero surprises. I'll start using Win 10 more when I have some spare time.
"I love it when a plan comes together"

best
PHubb

I need some more time with Windows 10. My home is upgraded, but I remain on Win7 on my work machines until the business decides to upgraded.

So far I like it. It seems faster slightly, but hard to tell. I got off windows media center a while ago, so having that gone isn't a big deal anymore.

Any way to perform the same steps on Ubuntu? (I'm not experienced Linux user)
I have found that there is wimlib (ImageX alternative), but what about bcdboot and etc?