How to set zfs mount parameters?

A

Annalesa

I manually installed FreeBSD on ZFS, but I only set up mounting zroot/ROOT/default to /. I noticed the default Auto(ZFS) installer mounts several other locations. What parameters (like recordsize, compress, etc) do I need to set for mounting these places?
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Each zfs command is logged in the history of a zpool. That history is a rich treasure source for forensics as it cannot be altered. You get it by zpool history.

Now have a look on the very beginning of that history done by the bsdinstaller if choosen to use it for RELEASE-15.0:
Code: 
# zpool history
History for 'poolname':
2026-01-28.13:52:06 zpool create -o altroot=/mnt -O compression=on -O atime=off -m none -f poolname ada0p3
2026-01-28.13:52:06 zfs create -o mountpoint=none poolname/ROOT
2026-01-28.13:52:06 zfs create -o mountpoint=/ poolname/ROOT/default
2026-01-28.13:52:06 zfs create -o mountpoint=/home poolname/home
2026-01-28.13:52:06 zfs create -o mountpoint=/tmp -o exec=on -o setuid=off poolname/tmp
2026-01-28.13:52:06 zfs create -o mountpoint=/usr -o canmount=off poolname/usr
2026-01-28.13:52:06 zfs create -o setuid=off poolname/usr/ports
2026-01-28.13:52:07 zfs create poolname/usr/src
2026-01-28.13:52:07 zfs create -o mountpoint=/var -o canmount=off poolname/var
2026-01-28.13:52:07 zfs create -o exec=off -o setuid=off poolname/var/audit
2026-01-28.13:52:07 zfs create -o exec=off -o setuid=off poolname/var/crash
2026-01-28.13:52:07 zfs create -o exec=off -o setuid=off poolname/var/log
2026-01-28.13:52:07 zfs create -o atime=on poolname/var/mail
2026-01-28.13:52:07 zfs create -o setuid=off poolname/var/tmp
2026-01-28.13:52:07 zfs set mountpoint=/poolname poolname
2026-01-28.13:52:07 zpool set bootfs=poolname/ROOT/default poolname
2026-01-28.13:52:07 zpool set cachefile=/mnt/boot/zfs/zpool.cache poolname
2026-01-28.13:52:07 zfs set canmount=noauto poolname/ROOT/default
2026-01-28.14:50:06 zfs create poolname/usr/local
The last command 1 hour after the installation I did manually.
 
The reference I use is in release/tools/vmimage.subr:

Code: 
        cd ${DESTDIR} && ${MAKEFS} -t zfs ${MAKEFSARGS} \
            -o poolname=zroot -o bootfs=zroot/ROOT/default -o rootpath=/ \
            -o fs=zroot\;mountpoint=none \
            -o fs=zroot/ROOT\;mountpoint=none \
            -o fs=zroot/ROOT/default\;mountpoint=/\;canmount=noauto \
            -o fs=zroot/home\;mountpoint=/home \
            -o fs=zroot/tmp\;mountpoint=/tmp\;exec=on\;setuid=off \
            -o fs=zroot/usr\;mountpoint=/usr\;canmount=off \
            -o fs=zroot/usr/ports\;setuid=off \
            -o fs=zroot/usr/src \
            -o fs=zroot/usr/obj \
            -o fs=zroot/var\;mountpoint=/var\;canmount=off \
            -o fs=zroot/var/audit\;setuid=off\;exec=off \
            -o fs=zroot/var/crash\;setuid=off\;exec=off \
            -o fs=zroot/var/log\;setuid=off\;exec=off \
            -o fs=zroot/var/mail\;atime=on \
            -o fs=zroot/var/tmp\;setuid=off \
            ${VMBASE} ./METALOG

It's also available in (imo) less clear form in usr.sbin/bsdinstall/scripts/zfsboot, which is what bsdinstall(8) calls.
 
your setup, with a single boot/ROOT/default is not valid for boot environments. a manual install has to set up the datasets as specified above. back up important files and reinstall properly.
 
Lots of good info here. One that I've used has been "do a default install into a VM and then look at zpool history". That will give you a record of what datasets are created by default, the default properties, etc. That is your baseline if you do manual stuff. Things like compression are not very interesting, but mountpoints and canmount are. Recordsize becomes interesting if a dataset is being used for DB stuff but for most things the default (I think is 4K) covers most things.
Boot Environments get interesting, again do a default install into a VM and study what has been created.
 
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