Error in /boot/loader.conf gives me a mountroot> prompt

M

Michael Faklis

I was adding packages, on a quest to get all of my built-in devices working, and got a note to add vfs.root.mountfrom=zfs:tank to /boot/loader.conf. Upon reboot I get a string of lines Solaris: NOTICE: Cannot find the pool label for 'tank', them Mounting from zfs:tank failed with error 5., ending up with a prompt mountroot>. I know I must remove that offensive line from loader.conf, but I can't get past that mountroot> prompt.

I attempted booting from a live CD, but I find myself clueless how to get the filesystem on my hard disk mounted in this live CD environment.

I request some direction as to how to get this fixed.

I'm running FreeBSD 12.1 Release amd64 downloaded 2020Mar09. The live CD is also from the same release. I'm using an old MacBook (late 2006 model). My hard disk used the ZFS filesystem with the default "use entire disk".
 
Elazar said:
Can you boot into single user mode?

Or, in the live CD, chose the option shell. Figure 2.3, “Welcome Menu”
There you should be able to mount your zfs partition. e.g. mount /dev/ada0p2 -o rw /mnt. Then edit the file /boot/loader.conf, with either ee, or vi..

But I am not 100% sure on that. ;D
Click to expand...
Y
20-100-2fe said:
Can you try and type zfs:zroot/ROOT/default at the mountroot> prompt?
Click to expand...
Thank you. This worked like a charm, so I was able to fix the problem in loader.conf.

Would you be able to tell me where I should have been able to learn this?
 
This kind of problem doesn't allow to boot in single user mode since the system can't mount the root anyway.
You can also boot on a FreeBSD disk/stick, import the pool & zfs mount zroot/ROOT/default, but it's far longer than the 20-100-2fe solution.

FYI, the solution is writed on the screen just before mountroot> among other typical answers (depending the file system you actually use).

PS : also, take a look at the boot environments ( bectl). It's useful when you are unsure about the change you make in vital configuration files.
 
Michael Faklis said:
Thank you. This worked like a charm, so I was able to fix the problem in loader.conf.

Would you be able to tell me where I should have been able to learn this?
Click to expand...

The name 'tank' appears in the Handbook and other documents about ZFS, it's not a real name.
When you install FreeBSD (e.g. in a VM) and type 'mount', you see the dataset mounted on / is 'zroot/ROOT/default'.
The error message says it can't find zfs:tank, so the expected syntax is zfs:<dataset>, hence zfs:zroot/ROOT/default.
 
Messing up one's loader.conf file is one of those painful experiences every FreeBSD user goes through at some point.
 
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