For me, the only drawback for corporations is the 6 month upgrade. There is no LTS on OpenBSD.
I use OpenBSD as a workstation and it works great, but in a production environment I doubt I would use OpenBSD for critical items, mainly because no LTS.
It is a sad state of affairs because Companies do not want nor will want a system you need to upgrade so often even if its security very good.
On the other hand though, updates on OpenBSD are the most painless updates I have ever done. I am more concerned about it's usage of UFS instead of something more robust for drives.
I'm grossly generalizing here, but it seems like OpenBSD boxes seem to be commonly used for the sorts of things that don't write a lot of data to local drives, except maybe logfiles. You can obviously use it for fileservers and such but I don't recall ever seeing that in the wild. So in that situation, UFS is fine.
(IMO it's fine for heavier-write cases, too. It's just especially alright for the common deployment case where it's practically read-only anyway.)
I've used it as a mail server, a web server, and a database (postgres) server. It's also my main desktop OS. Did/does fine, but I never really stressed it. I would certainly welcome a more capable filesystem option, as well as something like logical volumes, but I can't say that ufs has ever failed me.
You'll definitely want to have it on a UPS to avoid some potentially long and sometimes manual intervention on fscks after a power failure. And of course, backups for anything important.
> updates on OpenBSD are the most painless updates I have ever done
I see we have a post-syspatch (6.1 - 2017), post-sysupgrade (6.6 - 2019) OpenBSD user in our midsts. ;D
You are positively a newbie in the OpenBSD world !
Some of us are old enough to remember when OpenBSD updates were a complete pain in the ass in involving downloading shit to /usr/src and compiling it yourself !
According to Wikipedia, Debian has had apt since 1998.
My point is OpenBSD didn't have binary updates until well into the 2000's as mentioned above. Initially in 2017 with syspatch and the finally full coverage in 2019 when sysupgrade came along.
As you can see on some old OpenBSD Mailing List posts[1] there was a high degree of resistance to the very idea of binary updates. People even being called trolls when they brought up the subject[2] or being told they "don't understand the philosophy of the system"[3]
I just felt it was an important point of clarification on your original post. Yes, I agree, OpenBSD updates are painless ... now, today. But until very recent history they were far from painless.
Yet companies insist on enabling unattended upgrades at least for "security" patches, which have introduced breakage or even their own vulnerabilities in the past (Crowdstrike was a recent dramatic example).
OpenBSD will just tell you that maintaining an LTS release is not one of their goals and if that's what you need you'll be better served by running another OS.
I think it depends on your needs. Working corporate environments with 1000+ hosts, LTS operating systems are big help. On the other hand, for smaller cases, call it a work group or smaller, I think OpenBSD provides a base system that doesn't typically make drastic changes, along with a ports collection that does a pretty good job of keeping up with the third party applications. It's a good balance. I've recently seen some "Immutable" Linux distributions that are basically spins of upstream distributions. They leave the inherited distribution mostly alone and load the extras using Flatpak or the like. Sounds similar to BSD ports in a way.
I use OpenBSD as a workstation and it works great, but in a production environment I doubt I would use OpenBSD for critical items, mainly because no LTS.
It is a sad state of affairs because Companies do not want nor will want a system you need to upgrade so often even if its security very good.