How can I boot NetBSD from a different HD?

sn0w

Hey everyone.
(First off: I'm a newcomer to both BSD and this forum, so I apologize in advance if I posted in the wrong place or if the solution is embarrassingly obvious.)

What's the right way™ to boot NetBSD from a different physical drive than the one it's installed on?

I'm planning to run NetBSD on an HP Microserver (Gen 8), which has quirky booting behavior.
Without going into too much gory detail, the problem is that the server's only SATA port is not recognized by the BIOS unless all other drives are unplugged, or unless hardware RAID is enabled. (And neither is an option for me.)
What does always work though is booting from any of the USB ports or the internal card reader, so until now (with Linux) I simply threw /boot/ and GRUB onto a microSD and called it a day.

I tried to replicate that kind of setup with NetBSD, but for the life of me can't get it to work.
Tried fiddling around with installboot, fdisk, and disklabel for hours on end, but it seems like I'm either missing something in the manpages or generally misunderstand how the boot process works in NetBSD.
First off, none of the tools seem to toggle the MBR boot flag, which causes my buggy BIOS to completely ignore the device at startup. Secondly, when I "manually" toggle that flag the bootloader does launch, but instantly exits, claiming that the /boot file can't be found (despite the file being there on both the microSD and the HDD).
This was the case with both FFS w. bootxx_ffsv2 and FAT32 w. bootxx_msdos.

Any kind of hints/pointers are appreciated 👀
Thanks

20-100

sn0w Secondly, when I "manually" toggle that flag the bootloader does launch, but instantly exits, claiming that the /boot file can't be found

Maybe your boot USB device name likely changed, e.g. during installation, your installation medium was /dev/sd0 and your target boot drive /dev/sd1, but with the installation medium removed, your boot drive becomes /dev/sd0 and / can no longer be mounted. Check /etc/fstab on your boot drive.

rvp

Are you OK with using GPT instead of MBR for your partitions?

sn0w

rvp Are you OK with using GPT [...]

I'd love to, but sadly this machine doesn't support EFI :/
The only place where I can (and already do) use GPT is to make the >2T data disks work.

kamil

There is an option to create a thin boot device (like cgdroot) on an USB device and chroot into the larger disk for regular / mount. Maybe you could already use cgdroot or zfsroot for this instead of creating your own setup.

sn0w

Alright, I got it to work after all and - as suspected - it was my own fault.
Thanks for the help though.

After reading up on kamil's proposed solution, I noticed that newfs defaults to FFSv1 format (meaning I've been using the wrong primary bootstrap), and also found out that marking the slice where the secondary bootstrap resides as "active" (somewhat surprisingly) solves my MBR-flag issue.
whoops 😓

So yeah, in case anyone else ever runs into this problem, creating a single ("active") NetBSD slice containing a 4.2BSD (a) partition on my SD, formatting it as FFSv1, throwing /boot and a custom boot.cfg (with menu=:boot hd05a:netbsd) on there, and finally running installboot with bootxx_ffsv1 did the trick.

rvp

sn0w Alright, I got it to work after...

20-100 Maybe your boot USB device name likely changed

Right. Which was why I was going to suggest using the NAME=LABEL syntax for identifying disks if GPT was an option. Works everywhere on NetBSD: in the bootloader, in /etc/fstab, to the mount command, ...