For me a long time ago an upgrade meant buy new hard drives, do a reinstall, and copy either the entire old drive or main data dirs onto the computer.

Now my data volumes are separate from the system. I used raid for redundancy on the physical machine with another drive for differential filesystem level backups (snapshot every day for 60 days with only differential storage cost, see rdiff-backup). When I upgrade I just add new drives, assign them into the raid, wait for them to sync, and remove the old drives. By generational I mean my storage and how I do things aren't going to change when I reset things like they used to. All my data is outside the system I'm using and must be attached.

I can for example, spin up an AWS machine, run the package install commands for the apps I normally use, VPN to my fileserver and mount my home directory and project volumes, and in quite literally about 15-30 minutes have the exact same environment as I do at my house. CFEngine et al would speed that up quite a bit.

Thanks for the explanation, super helpful.

You are welcome. I'd have to say the biggest benefit for me personally is the distinct separation and permanence leads me to keep it very organized. When I had my files 'in' my system the lines blurred and things got spread all over the place. I still keep my download dir on the base system and only things i really care about make it to the data drive so there isn't much pollution. I'm a bit scatterbrained in that regard and this method accidentally solved that.

That sounds like a good setup to keep things where they belong. Thanks.

What raid system are you using to allow for adding arbitrary drives?

Software raid with LVM. For my primary storage pool I created a raid1 pair, encrypted with an NVME cache drive, then created an LVM PV nested on that, LVM within LVM to dish out volumes that all share those lower level benefits.