Something I've really come to appreciate with OpenBSD is the stability and ease of in-place upgrades. I'm not very familiar with FreeBSD, but from what I've read it seems it too has stable, straightforward, in-place version upgrades. I'd love to hear people's experiences.
I've found with Linux distributions that aren't rolling releases, things tend to break in annoying and insidious ways, such that you generally need to, or at least it is strongly advisable to, fresh install each time.
This is probably of less importance given the demise of the monolithic server, but for my own server, I really appreciate it and the avoidance of reconfiguring everything.
Usually, the upgrades are seamless (freebsd-update(8)[0]); system files that change between releases are looped through with some help of sdiff(1)[1] with relatively few surprises jumping dot releases (12.3 -> 12.4).
However, major pkg upgrades also bring their fair share of config changes; and those major pkg upgrades usually happen during major version changes (11 -> 12). Can't remember how I did it, but at one point I had an ancient nextcloud running on a recent FreeBSD system where a pkg upgrade broke everything in a spectacular fashion.
The latest OpenBSD upgrade though (7.1 -> 7.2) did break an important base tool I used (dhclient(8)) by dumbing it down to a lesser version that is less capable (no auth) (but probably better written)[2], so YMMV.
> Changed dhclient(8) to defer to dhcpleased(8) by doing execve ifconfig and providing syslog warnings about deprecated options.
> I've found with Linux distributions that aren't rolling releases, things tend to break in annoying and insidious ways, such that you generally need to, or at least it is strongly advisable to, fresh install each time.
Debian has historically been good for in-place upgrades. I first encountered the 'fresh install' recommendation on Ubuntu, which was a shame since Ubuntu is based on Debian :(
It does have a solid and well documented upgrade process, provided you're on the latest stable version prior to executing the upgrade.
Fall behind by 3 or 4 versions and it's a long laborious task to upgrade each one. For products containing the OS which are shipped out to customers (NAS, firewalls, appliances, etc) this process might be too high risk, so it's easier to never upgrade - but ship new hardware, usually in the form of a new product.
(This is from personal experience taking on a client who still ran internet-facing FreeBSD 9.x servers. Lift & shift to the latest FreeBSD 13.x was far safer)
I'm not personally familiar with any commercial products shipping OpenBSD, but it was my understanding that the "proper" way to do this is to fork the OpenBSD build infrastructure, or at least build your own release tarballs, and basically push your own OpenBSD'ish distro. AFAIU, the binary patching and upgrade frameworks make some (limited?) effort to accommodate the creation and maintenance of bespoke releases.
But maybe doing it the "proper" way is too difficult or opaque, incentivizing vendors (even more than they usually are) to simply abandon released models.
> I've found with Linux distributions that aren't rolling releases, things tend to break in annoying and insidious ways, such that you generally need to, or at least it is strongly advisable to, fresh install each time.
I think this is generally not true, at least of the major distributions. Others have already commented about Debian and Ubuntu, to which I want to add that updating Fedora over many, many releases has been completely seamless for me. The dnf system-upgrade plugin Just Works.
OpenBSD's in-place upgrades and binary patches are wonderful for keeping the system up-to-date. I've even successfully done a remote upgrade after ensuring there was enough space for the upgrade files.
I remember the old days where one had to manually compile and install the patches (instructions were provided), and where one had to build the entire kernel and userspace if you wanted to run -stable. A good learning experience and exercise, but I don't miss it. :)
Binary upgrades on FreeBSD are fine. I rarely compile my own kernel these days, but even when I did needed a custom kernel I never had any issues. It just works, For me FreeBSD and OpenBSD needs much less maintenance than Linux.
I've found with Linux distributions that aren't rolling releases, things tend to break in annoying and insidious ways, such that you generally need to, or at least it is strongly advisable to, fresh install each time.
This is probably of less importance given the demise of the monolithic server, but for my own server, I really appreciate it and the avoidance of reconfiguring everything.