LR Classic solution:
I would like to comment on what, you say you want to do and what you might consider doing.
Let's take the case of what I think is very common with many if not most serious photographers. You work on a home desktop, or fairly powerful laptop connected to a hub that has high-end editing monitor or dual monitors on the desk. . Let's call that the home studio. That home studio has a 32-inch 4K IPS (or soon - mini-LED). It has a late model CPU and boots off of a fast internal M.2 PCIe 4 (soon to be 5) SSD. On that SSD is your OS, Adobe programs (LR) and your one and only master LR Master Catalog. In your case, since you have less than 2 TB worth of raw files, you put all of your raw files on a second SSD (2, 4 or 8 TB as you grow) and it is installed internally or connected externally on a fast USB-C port (TB3/4 or USB 3.2 Gen 2 or USB 4).
That is where you do all of your home LR work because that machine is a joy to work on, mainly because of the incredible monitor and super-fast rig.
Your second LR machine is the laptop. The laptop is for doing LR work while away from the house on shoots, trips or travel. When you get home, the folder of raw files that you shot and edited are then quickly and easily transferred to the LR Master Catalog that is on your Home Studio. Then you delete all those files from your laptop. Your only LR catalog is on the Home Studio. Your image files are all on a single drive and backed up at least 3 times to other single drives.
What I described above has an even sexier version, and one that more photographers will utilize soon. You do everything off of one powerful new Windows or MacBook Pro 16-inch laptop (with M2 Ultra chip) and you have no desktop system. On the laptop is the Master (and only LR Catalog) and if you have less than 4TB of raw files, all of your image files. Everything is on that laptop (backed up to external drives of course). When at home, you quickly connect it to a TB4 Hub that has the monitor or monitors I described connected to the Hub, along with external storage and backups. When you want to work elsewhere in the house or on the road, you disconnect one cable and walk away with the laptop. No syncing catalogs. Everything simple and powerful. Ultimate flexibility and capability. That is allowed by advancing tech and new, very powerful laptops.
17 Clear Advantages:
1. You avoid the mess of trying to sync LR and LR Classic.
2. You avoid the mess of trying to have all of your raw files stored in the cloud that requires fast internet wherever you are in the world.
3. Most of your LR work is done on a fast home studio (or the single laptop solution) that has everything on it.
4. You experience the joy of using a top-end 32-inch professional 4K monitor, which is affordable now and was not before. That dramatically improves your photography enjoyment and your LR editing work.
5. You have one catalog and only one catalog, and that catalog is on the same fast SSD as your OS and LR program and that is on your home studio (or the single laptop).
6. LR runs at warp speed on that one good Home Studio (or laptop connected to hub).
7. Your raw files are on one fast, reliable SSD and backed up to other single disks.
8. You have a laptop with LR Classic and you use it for all work away from the home studio. You then use one of several methods for getting your raw files you shot and the edits you made into your home studio - the data disk and the catalog synced.
9. Simplicity - Speed - Reliability.
10. Avoids RAID
11. Avoids NAS.
12. Avoids the daily pile of sync issues we read about here on this forum.
13. Maximizes new tech while also saving money (if you shop smart and study).
14. Simple backup solution.
15. Moves you to SSDs and away from HDDs.
15. Maximizes the capabilities of LR while avoiding its weaknesses.
16. Will make you happy.
17. Won't make you sad.
Thank you for that thorough explanation. This sounds like a possibility. Is there an idiot's guide to the smart preview thing?
Over the weekend I opened up Lightroom (the other one, not Classic) and see that there are 743 photos there. I have NO CLUE how they got there. I cannot find any corresponding folder or collection in my LRC catalog that includes that quantity or the specific collection of photos included, so cannot see that some collection or other "synced" by accident. (By accident I mean only "not on purpose.") It includes photos from my iPhone taken as recently as 2 weeks ago, along with a variety of photos and videos spanning a 12 year period from iPhones and my "regular" cameras, and--in most cases--having no universal common metadata or attributes that I can identify. It includes SOME photos from my Apple Photos collection, but not all. It includes SOME photos taken from a trip to Death Valley three years ago, but not all. It includes raw, tif's and jpg's. If the "master" has both a raw and a jpg from when the image was captured, SOMETIMES this phantom catalog will include both, sometimes not.
For reference, my MAIN folder of masters includes 92,574 files, spanning years from 1998 to the present. Stored on an external SSD, backed up to two other ED's plus on Backblaze. I'm a backup fanatic, which I think sometimes results in folders replicating themselves with, shall we say, less "intentionality" than I prefer. My main .lrcat resides on my main machine internal HDD. Also backed up all over the place.
It seems completely random. And because I don't know how they got there, or if they're previews, smart previews or replicants of masters, I don't want to just clean out the catalog and start over. The one thing I can say is that, if I access my Adobe account online, this catalog seems to be the same as that. Or so it appears. Both have 743 photos. I have not spot-checked for complete consistency but that would seem likely.
I can't find where on my desktop these photos (or the versions of them in LR) are stored unless I "edit in photoshop" and click on the file name in the upper left and click "show in finder." In which case it takes me to some temp folder buried deep in the sys files, and not to the master file. So I suspect these 743 photos are all online only and can be safely deleted. But not knowing how they got there in the first place is driving my batty. The file names are the same as in my .lrcat, and I can find them that way, so I have to assume that this phantom catalog got exported or synced from there.
If I go to my profile online or in LR check "my account," it says I'm using 12.1 gb of 120 gb. What? Where do I have a 120 gb account? My Creative Cloud account includes 20 gb. Not 120 gb. That same info panel offers me the app to "delete LR library." Again, I don't know what I'm deleting or how it even got there in the first place.
If I do delete, I will--again--back up my .lrcat to my main ED, and disconnect it before doing so.
I also see that I can migrate a LRC catalog to LR "only once," so I'm not sure how that impacts things. I feel like I should create a small .lrcat from my main .lrcat and migrate that just to see what happens.
Oh, the perils of Pauline.