Not surprised there was a tool, but I don't remember it. :) most of my time at Yahoo was on 4.x, so minor upgrades only would have been fine. (Some 6 and 7 towards the end, but also a little bit of RHEL, which I was happy to get away from)
I wonder if FreeBSD would benefit from some documentation or packaging to make this more of a covered area?
Personally, the times I upgraded a FreeBSD box the process felt very smooth. To the point that I’m trying to understand @rsyncs point and seem to be missing something critical.
FreeBSD has a tool for binary upgrades now, and has had a process for source based upgrades forever. This is all documented in the FreeBSD Handbook, and I'd be surprised if the source based upgrade wasn't in there since the beginning of the Handbook, which I think came out with FreeBSD-3.
But, darkhelmet and I were discussing updating FreeBSD at Yahoo; doing the update from the Handbook wouldn't be the right way to do it, because you would miss out on Yahoo specific patches, which were likely required for some key Yahoo software. I don't think it was common knowledge how to do it, so some documentation might have been nice, but mostly teams at Yahoo just didn't do it at that time for better or worse.
The tooling at Y! sounded quite good from the descriptions. Kind of confirmed my thoughts that the proper way to run a FreeBSD system is to make hopping versions not affect hosted applications through specific tooling and/or infrastructure. Especially the bit about building on older versions and such. Not really sure what more would address the version complaints from @rsync.
There could be policy reasons why someone may decent not to do it: if you have a large fleet of cattle machines it may be easier to just redeploy from scratch. Home(lab) users and pet machines at companies may do otherwise.
