SATA/ACHI driver cannot start on external bootcamp install.

Thanks for the reply Loner 🙂

I did until recently have two valid installations of Windows 10 on both the internal and external drives, as I wanted to be sure it was working well on the external SSD for a while. However I think ever since I booted Windows from the SSD it has been unable to see the internal partition/drive. Currently Windows 10 is only installed on the SSD and I have formatted the internal HDD to have a NTFS partition and a HFS+ one.

Perhaps something to do with cloning Windows, so it didn't update the settings? Not sure how it would affect the driver/controller for the internal SATA disk though as that hasn't changed aside from the reformatting of it but that was quite recent.

I did go with Winclone in the end, after considering other methods, so could be related.

Device Manager reports the controller/driver as Intel 8 Series C220 SATA AHCI Controller, which seems to be part of the Bootcamp drivers as it's not the default that comes in Windows.

I think I did try uninstalling the driver and reverting back to the default driver, but I dont think it helped, unless I didn't restart after.

A similar setup to what I have then except my SSD is connected via USB. I might see what the Samsung software says too like above. I can see the Intel SATA/AHCI controller there without any errors too. I did notice that the driver version was from 2006 though, so I wonder if it's worth checking for an update from Intel.

That said, it was working after one restart earlier but then after later after another restart it now isn't. I will uninstall it and restart for now, and also check the Samsung software.

However, I believe that is the driver responsible for internal drives even if not in AHCI mode.

Unfortunately since then after I did a couple of driver updates with bootcamp and Intel my Windows installation seems to freeze shortly after getting to the logo loading screen and I have yet to figure out why. Even after erasing the partition and restoring it from the Winclone image the problem persists.

However, this would require a new post, but thanks for your help on this one. Perhaps if I manage to sort Windows out the original problem will be resolved too.

I have yes, it's my plan C. Although from research Windows won't natively install on a USB/external drive I believe, so you need to do some modifications using programs like WinToUSB.

Also I just avoided doing this because of the hassle of installing all programs and drivers again. Windows only has an issue starting when done via bootcamp however, as when I use VMWare to create a VM from the bootcamp drive it doesn't have any issues.

It's a mid 2015 Retina 5K 27" iMac, so should hope it is new enough.

Still not sure why when it was running on the SSD before that driver would fail though for the internal drive, or if that is the cause of Windows being unable to see it. However when running it from the internal drive it was running fine, else I guess it wouldn't boot up.

I am pretty sure it's a driver issue as to why it would freeze shortly after booting, although why it still persisted after the partition was erased is strange. I am currently restoring a new clone copy I created from the internal HD to the SSD partition and will hope for the best.

That's the thing, I had Windows running on the USB SSD for a week before I realised the internal drive wasn't being picked up by Windows, however aside from that it was working perfectly.

You may be right about UUIDs though, I was thinking if we could modify or delete them from the registry if that was confusing the driver. EDIT: Maybe not this, was hoping for somethin in registry that maps disks and partitions.

Sadly thunderbolt is too expensive and not really not necessary since it exceeds the SATA speed of the drive, also I believe 2015 iMacs have TB2, which is less common these days. The only issue with getting bootcamp to work on an external USB drive is that you need to modify the registry to tell Windows to load the USB drivers first or you get an "Inaccessible Boot Drive" screen.