[TUTORIAL] Troubleshooting faulty zfs.config

inDane

Well-Known Member
Jan 11, 2019
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I've made a mistake today.

I was trying to modify l2arc_write_max and l2arc_write_boost.

What i did was: CAREFUL THIS IS WRONG
Code:
options zfs l2arc_write_max 67108864
options zfs l2arc_write_boost 134217728

it should be
Code:
options zfs l2arc_write_max=67108864
options zfs l2arc_write_boost=134217728


Reboot resulted in some error that said zfs module couldnt be loaded and there are invalid parameters...
My root is ony the ZFS.

Here is what I did to recover my system:
Code:
vi /etc/modprobe.d/zfs.conf
Press "i" to change to insert mode, edit the faulty lines and save the file via (ESC) -> :wq

Code:
mkdir /mnttmp
modprobe zfs
zpool import rpool
zfs set mountpoint=/mnttmp rpool/ROOT/pve-1
zpool export rpool 
# I had to do this several times; once for every subvolume. I dont know why. The message said it couldt be unmounted. Ignore it.
zpool import rpool
vi /mnttmp/etc/modprobe.d/zfs.conf
# Edit it like above.
zfs set mountpoint=/ rpool/ROOT/pve-1
zfs export rpool

Then I rebooted the machine and it worked again.

I hope this helps. I dont want to reproduce this right now to double check, but I think this was what I did.