I'm pretty sure your conclusion is wrong. If grub were installed on your ssd, you'd also get a grub-menu when the usb-hdd is disconnected.Jools wrote:So I would want grub to be on the part 1 of this usb disk, but it must have installed something on the boot partition of my ssd drive, therefore overriding the bcd. I believe so, because after the fsck, when the usb-disk was plugged in, my computer would always boot to that drive, irrespective of the fact that my ssd drive was selected as the boot drive in the bios. Therefore I drew the conclusion that one form of grub was put on this ssd drive.
* Are you sure, that in your bios settings (boot order) usb-drives do not come before sata drives?
* When the usb-disk is connected, and you use F11 (or similar) while booting to make a manual boot selection, and you choose the internal SATA disk - what happens?