Painless FreeBSD server migration
=================================
Some time ago the motherboard of one of my NUCs died.
With some improvisation I got everything working again. However,
this involved running 24/7 a machine that is loud and consumes
quite some electrical power. This machine runs in our living
room. Of course, this could only be a temporarily solution.
Replacement network server
--------------------------
Recently I got a "new" machine, to be used as a network server in
my home network. This HP EliteDesk 800 G2 Mini dates probably
from 2015, which make it around 8 or 9 years old.
To test it, I installed FreeBSD 14 on it, together with a few
jails, as well as vm-bhyve, complete with a virtual machine
running Debian. It ran stable, without any surprises, and I
decided to set it up as a central server.
New master jail
---------------
Having a fresh FreeBSD machine with the latest stable version was
a great occasion to start with a fresh master jail, also based on
FreeBSD 14.
This jail is kept untouched, as a basis for the other jails. The
snapshot of this jail makes it easy to create new jails.
IMAP- and STMP server
---------------------
The first step was to recreate the IMAP- and STMP server.
The previous IMAP- and STMP server was a jail, running an older
FreeBSD version.
Using zfs send and receive locally, I copied the master jail to a
new jail, as starting point for the new IMAP and STMP server. The
next step was to set up sendmail as STMP server, and Dovecot as
IMAP server.
The opendkim package makes it easy to setup DKIM. I copied the
sendmail configuration, the opendkim configuration, and the keys
for my domains from the previous server. After a restart sendmail
and opendkim worked fine.
I created a separate ZFS dataset for the Maildir and used
mount_nullfs to mount this in the jail. This makes it possible to
create snapshots of the Maildir, independent of snapshots of the
whole jail.
Migrating virtual machines
--------------------------
The virtual machines on the existing machine are all created with
vm-bhyve. The command "vm snapshot <vm>" creates a snapshot. The
command set zfs send / zfs receive migrates the virtual machines
to the new server and to the right location.
The package vm-bhyve is easy to install and configure.
All in all, the migration of the virtual machines went very
smooth.
Other jails
-----------
I did set up some other jails, again starting with using a local
zfs send / receive to copy the master jail. One of these jails
runs some local webservices, like Bepasty.
Again, in each jail the most dynamic part is on a separate ZFS
dataset that is nullfs-mounted into the jail.
All the jails are now based on FreeBSD 14.
Snapshots
---------
After finishing the setup of each jail, a snapshot of the jail
was created.
Every night a script creates a snapshot of each of the ZFS
datasets containing a dynamic part in the jails. The script
copies the snapshots using zfs send / zfs receive to another
machine.
Because of this, there is no need to frequently create new
snapshots of the entire jails. Only after an upgrade or other
change within the jail a new snapshot is needed.
The virtual machines are mostly used for writing software reviews
and for testing purposes. Depending on the task at hand, I use
virtual machines with Debian, Ubuntu, FreeBSD, or OpenBSD.
Immediately after the installation of the operating system I
create a snapshot. Next, I can install packages, install software,
and so on.
When the review is finished or the testing is done, a simple roll
back off the snapshot returns the virtual machine almost
instantaneously to the pristine install.
Creating a clone of a ZFS snapshot hardly takes any time. This is
a great blessing when multiple machines with the same operating
system are needed.
Next steps
----------
Most work is done, There are some final parts to set up, like
prose linting with Vale and Flycheck in the jail used for writing
texts.
The HP EliteDesk 800 G2 Mini has an empty slot for a 2.5 inch
SSD. Currently the 256 Gb M.2 NVMe is sufficient. Perhaps in
future I will replace it with a larger NVMe. For backup purposes,
adding a 2.5 inch SSD is also an option.
Considering the use of virtual machines, the amount of RAM will
probably be the first bottleneck. The maximum RAM in this machine
is 32 Gb (2 x 16 Gb SODIMM). I haven't check prices yet.
FreeBSD on ZFS is wonderful
---------------------------
Running FreeBSD, with jails and bhyve guests on ZFS is wonderful.
ZFS snapshots are easy copied to another machine, either to
recreate a jail, a virtual machine, or a data directory, or as a
backup method.
