Apple photos - referenced files

If you change the location of the referenced files Photos will lose the link to them and it's extremely difficult to relink them. This user tip describes the downsides to a referenced library: Disadvantages of a Referenced Library in Photos for Mac. You would be best served to consolidate your library and run it as a managed library. Then you can move it to any volume you'd like to run from there. However, the drive must be formatted OS X Extended (journaled) with ownership set to be ignored and directly connected to your Mac by cable.

No. The iCloud Drive is a syncing service and not off computer storage. It is what it is and must be used as is.

If you have Time Machine enabled you are backing up the library as it exists on your MBP.

There is no online facility that can store a Photos library and restore it in working condition. The server formats are not compatible with a Photos library ecosystem of file permissions and hard links.

I believe that Terence mentioned in another topic that Lightroom CC could store the originals in the cloud and operate. Correct me if I'm wrong on that, Terence.

Photos is not Aperture, which was well equipped in this area. If you change the path to the files then Photos will lose them. Next time you try and access the files it will ask you to locate it. Finding one photo should be enough to reconnect all the photos in that folder. But that will leave you working folder by folder. That, along with the absence of any file management tools means that I do not recommend using Photos in referenced mode, and if you really want to use that you're best off with an app that has the tools to manage it.

can I simply store the apple photos library files on icloud drive?

No. The library needs to be on a disk formatted Mac OS Extended (Journaled) or afps and with a direct connection (read:USB/Thunderbolt) to the Mac. Placing it on an inappropriately formatted drive or on a network share risks library corruption, poor performance and dataloss.

It's true. You pay a subscription but you get more.

There are two versions of Lightroom

a: Lightroom Classic is essentially the equivalent of Apple's Aperture, plus 5 years more development. It's a fully fledged, local raw processor and Digital Asset Manager. The files are on your HD.

b: Lightroom (earlier versions were called 'Lightroom CC') is a Cloud based app and is more like a souped up Photos.app. But there are few very significant differences. With LR the master files live in the cloud. You can choose - if you wish - to also have a local copy, on, say, an external HD as a failsafe, but it is not necessary. There are versions of LR for iPhone, iPad and AppleTV, as well as for Windows and Android devices, so it is really cross platform. The Phone version even offers its own camera. Similar to Photos, any changes/edits etc made on one device are synced across to the others. I have 78K images in LRCC and have them backed up locally as well. It works really well.

Like any subscription service I recommend you research what happens if you don't pay the sub. Find out what the consequences are. For instance, in the case of LRCC Adobe will store the images for a year - which gives you plenty of time to download them.