tn2fbsd

TrueNAS Core is no longer under active development, so it is time to migrate to FreeBSD.

This tool generates FreeBSD 15 configuration files from a TrueNAS Core 13.x configuration export.

tn2fbsd reads a TrueNAS Core configuration database and writes a freebsd/ directory containing configuration files at their real target paths, plus a MIGRATION.md describing the remaining manual steps.

Migration

Migrating from TrueNAS Core to FreeBSD is straightforward. Anyone with solid UNIX/Linux experience should be able to complete it.

The migration involves several manual steps. Below is an overview of the required migration tasks:

• Install FreeBSD 15.x on a new SSD/HDD (use a separate server with the same architecture)
• Run tn2fbsd to generate FreeBSD configuration files and a migration guide
• Copy the generated configuration files to the new FreeBSD installation
• Remove the SSD/HDD containing the TrueNAS operating system from the server
• Install the new FreeBSD SSD/HDD in the TrueNAS Core server
• Boot the server into single-user mode
• Perform the remaining manual migration steps
• Reboot into a fully functional FreeBSD server

Requirements

• Python 3.11+
• PyYAML (pip install -r requirements.txt)
• openssl in PATH (used to decrypt encrypted database fields such as SSH host keys and replication credentials)

Input

The input is the TrueNAS "Save Config" export created with "Export Secret Seed" enabled (System -> General -> Save Config). That export is a tar archive containing:

• freenas-v1.db — the configuration database
• pwenc_secret — the secret used to decrypt encrypted fields

Usage

./tn2fbsd.py [-o OUTPUT] EXPORT.tar

• EXPORT.tar — the export archive described above
• -o, --output — output directory (default: freebsd)

Example:

./tn2fbsd.py -o freebsd truenas.tar

Then read freebsd/MIGRATION.md and follow it: copy each generated file to the listed path on the FreeBSD system, apply the listed ownership, create the users and groups, and install the required packages.

Output

Path	Contents
etc/rc.conf	Base defaults, hostname, network, service enablement, RC tunables, system_advanced settings (e.g. powerd)
etc/resolv.conf, etc/hosts	DNS and hosts
etc/exports	NFS exports
etc/ssh/sshd_config	Base-system sshd configuration
etc/ssh/ssh_host_*	Migrated SSH host keys (private and public)
root/.ssh/authorized_keys	root's authorized_keys (only if included in the export)
etc/sysctl.conf	SYSCTL tunables (renamed/removed OIDs translated to FreeBSD 15.1), NFSv4 numeric-ownership sysctls
etc/periodic.conf	ZFS scrub tasks
etc/cron.d/tn2fbsd	Migrated cron jobs
boot/loader.conf, boot/loader.conf.local	Bootloader config, LOADER tunables, serial console
usr/local/etc/smb4.conf	Samba global settings and shares
usr/local/etc/zettarepl.yaml	Periodic snapshot and replication tasks
usr/local/etc/rc.d/zettarepl	rc.d service script for zettarepl
MIGRATION.md	ZFS pool import, file ownership, account creation commands, manual steps

Scope

Not all TrueNAS Core services will be migrated. Only the following migrations are currently available: network, users and groups, NFS, SMB, SSH (base-system sshd with its configuration and host keys), zettarepl (periodic snapshots and replication), ZFS scrub tasks, cron jobs, and tunables.

Migration is not available for AFP, WebDAV, iSCSI/block shares, plugins, virtual machines, jails, and the SNMP/SMART/NTP/FTP/rsync/DynDNS daemons.

Web GUI

The migration does not involve setting up a GUI. However, WebZFS is freely available. It is a modern web-based management interface for ZFS pools, datasets, snapshots, and SMART disk monitoring. This should make the transition from TrueNAS Core to FreeBSD more seamless.

Managing disks

TrueNAS partitions every data disk with a GPT scheme, an optional swap partition and a freebsd-zfs partition, then adds that partition to the pool by its GPT partition UUID (gptid/<uuid>) instead of the device name (da0p2). The gptid does not change when devices are renumbered, so pool membership stays stable. To keep managing disks in the same style on FreeBSD, reproduce these steps.

Preparing a disk

Replace da0 with the target device. TrueNAS reserves a 2 GiB swap partition per data disk (swapondrive); drop the swap line to use the whole disk for ZFS.

gpart create -s gpt da0
gpart add -a 4k -b 128 -t freebsd-swap -s 2G da0
gpart add -a 4k -t freebsd-zfs da0

Without a swap partition the ZFS partition takes the first slot:

gpart create -s gpt da0
gpart add -a 4k -b 128 -t freebsd-zfs da0

Look up the gptid of the freebsd-zfs partition (its rawuuid):

gpart list da0

Creating a new pool

Partition every disk first, then create the pool from the freebsd-zfs gptids. The options and dataset properties match the TrueNAS defaults (ashift=12, altroot=/mnt, lz4 compression, atime=off, passthrough ACLs):

zpool create -o ashift=12 -o autoexpand=on -o failmode=continue -o altroot=/mnt \
    -O atime=off -O compression=lz4 -O aclmode=passthrough -O aclinherit=passthrough \
    tank mirror /dev/gptid/<uuid-disk1> /dev/gptid/<uuid-disk2>

Use raidz1/raidz2/raidz3 or no keyword (stripe) in place of mirror as needed.

Adding disks to an existing pool

Partition the new disks as above, then add them by gptid. A new vdev extends the pool's capacity (match the existing vdev layout):

zpool add tank mirror /dev/gptid/<uuid-disk3> /dev/gptid/<uuid-disk4>

To grow an existing mirror instead, attach the new disk to a disk already in it:

zpool attach tank /dev/gptid/<uuid-existing> /dev/gptid/<uuid-new>

Trademark Notice

TrueNAS® is a registered trademark of iXsystems, Inc. This software is an independent project and is not affiliated with, sponsored by, or endorsed by iXsystems, Inc.