Re: GRUB2 doesn't read "boot" directory with different configuration file (in /boot/g
Some computers just have a problem booting from large external drives, but I never figured out why. For example, my Dell desktop PC from 2010 boots Linux fine at the far end of its 1 TB internal drive (near 900 GB out), boots fine from 160 GB USB drive, but cannot boot from 500 GB external drive (falls to grub rescue prompt). Even if I boot complete grub on internal drive and go to regular grub prompt (instead of rescue), it can see the root of the external drive and into boot, but not into boot/grub.
The same 500 GB USB drives boot Linux fine on older Dell and Toshiba laptops from 2006, so there is nothing wrong with grub or Ubuntu installation on those drives.
i5 650 3.2 GHz, 8 GB, nvidia GTX 750 Ti, 32" 1080p | i7-4700MQ, 8 GB, Intel HD 4600/nvidia GTX 765M, 15.6" 1080p | etc.