FreeBSD needs to boot from a
root partition containing
/boot, not from a separate
/boot partition. The latter is a Linux thing.
Having said that, it should be perfectly possible to put a boot partition (i.e. a root partition containing
/boot) onto a USB drive and have it (re)mount a ZFS root partition. I have very limited experience with ZFS, but it probably operates on pretty much the same principle as a
geli(8)-encrypted root partition, a setup I use frequently.
To illustrate, here's how the latter works on my laptop. In order to boot, I must insert a removable USB flash drive before powering on the machine. This flash drive contains a plaintext FreeBSD partition to boot from, which acts as a
temporary root partition. It contains
/boot, some encryption stuff (I'm too lazy to type passphrases so I use keyfiles) and nothing else. The file
/boot/loader.conf contains (among other things) the line
Code:
vfs.root.mountfrom="ufs:/dev/label/root"
which instructs the system to mount
/dev/label/root as the root filesystem. This is the actual root partition, residing inside a GELI encryption container on the hard drive, which has been encrypted entirely. Once the system has finished booting (or actually at some point during the boot process, but never mind that) the USB flash drive I had to boot from can be removed, without having to unmount it first.
I'm sure a similar setup is possible with ZFS instead of (or even alongside) encryption. Have you checked the
Howtos & FAQs section of this forum? Surely there must be a tutorial there for the setup you desire.
