I run Linux Mint on one SSD and Windows 7 on another.
Linux Mint SSD is on SATA 1; Windows 7 SSD is on SATA 2; 500GB empty drive on SATA 3.
I upgraded Windows 7 to Windows 10 and after getting it all set up and pretty, I decided to reboot and use Linux for the rest of the night.
Well, with my Windows Drive Connected, I tried booting into Linux but received the error: "Cannot mount drive /mnt/sdb1". So, I booted back into Windows 10 and everything Windows-wise was cool.
Here comes my screw up:
Fast forward to today (roughly 3 days later). I tried fixing my Linux Partition by unplugging the Windows Drive (since that would be the /sdb1 drive) and received the error: "The Disk Drive for UUID=<Drive Name Here> is not ready yet or not present". Using a LiveUSB, I tried mounting and using chroot to try and fix grub, but to no avail. I also tried reinstalling Linux Mint while keeping my /home partition, but with no success either. So, I decided to install another SSD that I wanted to add for games & misc. files since it was bigger. So, I opened up my computer, reorganized a bit and put all of the SSDs in (in the config at the start of my post) and connected all the power/SATA cables.
I had previously read that Windows 10 gets really pissy if you make any changes to hardware. Well, here comes the confusing part:
1. When only the Linux drive is connected, I get the "Disk Drive UUID" error.
2. When booting into Linux with the Linux Drive & Windows Drive Connected, I get the "Cannot mount Drive /mnt/sdb1" error.
3. When Booting into Windows WITHOUT the Linux Drive Connected, I get the BSOD error "A required device isn't connected or can't be accessed. 0xc0000225".
4. When booting into Windows WITH the Linux Drive connected, Windows 10 works just fine.
My hypothesis: Windows always wants to be first. When I upgraded to Windows 10, since my Linux Drive was in the 1st SATA slot, I think it bound the Windows Boot Manager & other Windows start up necessities to it as well. By doing this, it changed the UUID of my / or /boot partition so grub doesn't know where to look when booting. My concern is that I'm not sure how to separate these and to get them both to work. I was saving up for a backup drive, so I don't have any backups (luckily, this is for games. I'm only worried about some read-only files on my Linux Drive). I do not have any physical media for Windows 10, and would rather create a VM (and attempt GPU passthrough) than install Windows 7 SP1 from scratch and do all those damned updates. I'd prefer not to have to reinstall any OS, but I'll do it if we cannot find a solution to these two problems.
Please ask my any questions you may have and I'll try to get back to you ASAP. I have finals for school tomorrow, so this is really just a massive inconvenience. Thankfully, all my school work is on a laptop or synced to Dropbox.
I don't find it necessary, but to save anyone the trouble of asking, here are my parts:
CPU: Intel i5-4690k
GPU: Gigagyte WindForce GTX 970
RAM: 16GB G.Skill (4x4GB)
MOBO: MSI Z97S SLI Krait Edition
PSU: Seasonic G-Series 650W.
SSD: 2x Samsung EVO 850 (250GB), 1x Samsung EVO 850 (500GB)