Boot from one drive and load FreeBSD from another

[Stefan Bethke]

Am 11.01.2019 um 23:08 schrieb Walter Parker <walterp at gmail.com>:
> If I create a FreeBSD-boot partition on the SAS drive and a FreeBSD-zfs
> partition on the ZFS mirror, will the boot partition loader automatically
> find the ZFS pool? If not, is there anything special I can do to force a
> boot?

Set up a UFS filesystem on one of the disks that the BIOS can access and put everything under /boot into it. Install boot or gptboot (not zfsboot or gptzfsboot) with gpart, since loader will only work on that UFS filesystem.

Since loader can’t find your root file system (as the BIOS has no access to those disks), you need to set the path to the root filesystem in loader.conf (see loader.conf(3), vfs.root.mountfrom). For ZFS, that something like zfs:poolname/path/to/rootfs. This will instruct the kernel to mount root from that spec. Normally, loader figures this out automatically, by probing the disks for metadata (ZFS) or by analyzing fstab (UFS), but in your case, it can’t.

You’ll probably want to add an entry for /boot to your fstab, so updates will update the boot partition instead of the /boot directory on your ZFS root.


HTH,
Stefan

-- 
Stefan Bethke <stb at lassitu.de>   Fon +49 151 14070811