Thank you all for you comments. That clarifies it. I did in fact mean the directory /root, not the root file system. I apologize for the delayed response. I need to try to correct my profile or something so I get email when my post is answered.
The broad overview:
I have been “upgrading” as opposed to “installing”, even though many recommend “installing” for purposes of system hygiene and purity. Meaning, far as I can see, safer with fewer unexpected issues hooked to pre-existing system data. That’s nice, but…
“Installation” means manually reinstalling everything not provided by default. And resetting dozens (at least) of configuration tweaks. THAT, in practice, is a huge problem, for me anyway. Example: The StartMenu needs to be reset back in order since I use a custom structure which helps me see what I have available more or less quickly and easily years after installing something (which I often can’t quite remember the name of); perhaps that’s just an “easy” restore, but it goes on the list of before/after procedures which quickly grows and grows. Dozens, maybe hundreds of settings which I have found desirable over many years go away with an “install”. There may be this way or that way to save various things and “reinstall” somewhat more quickly. But one needs to maintain and find the list (how-to’s, config files, restore/reinstall procedures, etc, etc) from last time, and at least review all the procedures before use. It’s often 2-3 years between system upgrades and I have zero expectations of pretty much anything going right in that space (restoring/reinstalling my apps and settings after and “install”). This is based on a lot experience, and, of course, on my own work habits.
IOW, “installation” of new versions of systems is tantamount to throwing out all the productivity tweaks accumulated since last version change - and often many years prior - and this is a serious problem. Happily, thus far, “upgrade” appears to mostly work as expected, leaving most of my tools and settings alone. I personally have experienced few if any problems. Actually I did two glitches upgrading 15.4, but those seem a small price to pay compared with chasing all my apps and configs. The glitches: The upgrade script for local media wouldn’t go past the system check because it “lost” the media device. I upgraded manually, repo changes then "dup… The upgrade worked happily and all was well except one thing. It killed my wifi dongle, an rt82xxx chip which had survived the last three upgrades. After an hour of hassle, I just bought another dongle (RALINK) with a different chip that worked out of the box. I’m mostly good with the guys who engineer the upgrade procedures.
However, while I was pretty sure that /home would not be messed with, I wasn’t that sure about /root. I have been saving install media for the dozens of packages, mostly utilities, which I pull down, mostly from software.opensu… into a special user on /home. But most are useful and desirable for all users, and it would be cleaner/clearer to locate that kind of system wide file somewhere the data is not attached to a particular user and yet would persist through “upgrades”. /root seems the obvious place but I needed to get some specific exact info on the policy for /root across “upgrades”.
I think you’re probably correct that fstab has accumulated some road kill. I haven’t gone through it specifically looking, but I’ve noticed a few lines that I can’t relate to anything in particular. I may get around to looking eventually, but so far it doesn’t seem to have caused any problem. Possibly that’s because I’ve never used btrfs - never seen the ROI for the small systems I have to deal with. For me ext4 “ain’t broke” and my volume maps are very simple, pretty much flat. Eventually I’ll have to get real about snapshots and such as the predators move into our world and target us softies. Right now, I just do backups.
Again, thanks to all.