Vincent's blog

Cloning FreeBSD Jails with ZFS: Fast Copies, Hidden Dependencies

Sat, 10 Oct 2026 22:18:00 +0100

In my previous post I built a minimal thick jail from pkgbase packages and ended with a baseline ZFS snapshot. That snapshot is more than a safety net: it is a template. With a single command you can stamp out as many jails as you need, each one ready in a second and using almost no extra disk space.

But clones come with a property that surprises people: a ZFS clone is not a plain copy. It stays linked to the snapshot it came from, and that link decides what you can and cannot destroy later. In this post I clone one jail into four, list the few things that must be changed in each copy, explain how upgrades behave, and show three ways to deal with the dependency between a clone and its origin.

FreeBSD Thick Jails the pkgbase Way: A Minimal, Working Setup

Sat, 10 Oct 2026 21:19:00 +0100

For years, building a FreeBSD jail meant downloading base.txz, extracting it by hand, and later juggling freebsd-update(8) to keep it patched. With FreeBSD 15, the base system is also available as regular packages, a method known as pkgbase, and jails are where it shines: you install exactly the pieces you need, update them with the same tool you use for everything else, and keep the whole thing on its own ZFS dataset that can be snapshotted, rolled back and cloned in seconds.

In this post I build a minimal but functional thick jail (a full, self-contained copy of the userland) from scratch, from dataset creation to a running system with SSH. I also share the one mistake that cost me an afternoon, a userland newer than the host kernel that made the jail hang on shutdown, along with the commands to avoid or fix it. Everything here comes from a real FreeBSD 15.1 setup. Adapt the pool, dataset and network names to yours.

Converting a FreeBSD Jail with pkgbasify

Sat, 10 Oct 2026 09:40:00 +0100

For years, keeping a FreeBSD system up to date meant running freebsd-update(8), which patches the base system as a single, opaque block. pkgbase changes that model: the base system is split into ordinary packages that you can install, query and upgrade with pkg(8), just like any other software. The pkgbasify script can convert an existing installation, but it rewrites the whole base system, which makes it a poor first experiment on a machine you care about. A jail is a much better laboratory. It is isolated from the host, cheap to create and, with ZFS, trivial to roll back. In this article I walk through converting a classic jail to pkgbase from start to finish, including the one jail parameter that makes the conversion fail if you forget it. I then show how to upgrade the result to a newer minor release, all without touching the host.

What I did at EuroBSD Brussels

Tue, 22 Sep 2026 22:34:00 +0100

Three days in Brussels with the people who build BSD. A training with Kirk McKusick, talks on FreeBSD's future, a museum visit by tram, and long conversations with names I'd only known from mailing lists. I went in wondering how many people actually make a living from BSD. I came back with an answer, a few new friends, and a lot of respect for a community that mostly does this for love, not money.

Blogging since a decade

Sun, 16 Aug 2026 21:47:00 +0100

This month, this blog turns 10 years old.

I want to use this anniversary post to look back at everything I've written over the last decade: what has stayed the same, what has evolved, and what I've replaced along the way.

UTF8 email with DMA: DragonFly Mail Agent

Sat, 30 May 2026 20:40:00 +0100

In the context of the DMA developped in this post, this blog post improve it so to have accents and all nice icons in emails delivered by DMA

I test my new version of Fapws4 against other wsgi solutions and even against apache

Sat, 14 Mar 2026 22:04:00 +0100

I've made lot of modificaitons inside Fapws4 those last days/weeks. It remains a strong and very fast WSGI server offering all flexibility of Python. This is mainly than,ks to the libuv library and the picohttp parser. This blog will show how Fapws4 resist to massive requests and to compare results with other SWGI solutions. I will even compare it with apache24.

AMDGPU crash with FreeBSD 15.0 on my laptop. Why and what are possible solutions

Wed, 11 Mar 2026 20:58:00 +0100

I recently upgraded my machine from FreeBSD 14.3 to 15.0-RELEASE. The upgrade itself went smoothly enough, but when I rebooted into the new system, I was greeted with a kernel panic. The culprit: amdgpu.

In this blog, I will share some details and will explain the workaround I've put in place

ZFS send and ZFS received do not only send your files

Fri, 06 Mar 2026 21:15:00 +0100

It's important to understand that ZFS is not only a filesystem. It's also a set of parameters. And those parameters are send together with the files. One of the main paramtere is the mountpoint. Indeed, we must avoid that several datasets have the same mountpoints: /var, /home, ... This blog post will explain some précautions before sending datasets of several machines to a central machine.

Just for my memory, few commands to update a FreeBSD 14

Thu, 05 Mar 2026 22:42:00 +0100

I'm using a remote machine where I push zfs dataset 2 or 3 times per year. This blog will reminds me the steps I have to perform to update this machine. Since I rarely boot it, it's often off-sync and requires updates. This blog explain how I did update and upgrade of my FreeBSD machines