I've successfully followed these instructions to get a Raspberry Pi 3 to boot from a USB hard drive. Broadly speaking, it works very well.
Unfortunately, it seems that the root (ext4) partition doesn't get unmounted cleanly when I reboot (from the GUI or from the command line). This means that when it then tries to boot up, I just get a black screen.
In order to get it then to power up, I have to attach the hard drive to a laptop and
fsck the ext4 partition. Once I've done that, I can put it back into the Pi, and it'll boot cleanly.
That's really annoying, though. How can I either
- force it to
fsckat boot time, or
- make it unmount cleanly when it powers down?
I've tried various options in
cmdline.txt, but with no success. I'm not even seeing the coloured splash screen, so I have a feeling it's not even getting as far as reading
cmdline.txt, but it's hard to verify this.