I manage my picture library in Photos, the size of which is currently about 120 GB. For backup and to have online access to all my pictures I would like to sync the library with the cloud. However, I do not want to be fully dependent on Apple, therefore I would like to sync to OneDrive. On the other side, I also do not want to miss the comfort of Photos - besides, all my pictures are sorted in Albums, and that we would be quite painful to organise again in a new management software. Also, I want to keep Photos managing the importing and storing of the files.
Now, I could copy the entire library to OneDrive (OneDrive app is running on my iMac) and Photos would work fine, but then due to the constant work of photoanalysisd and its friends in the background, there would be a daily additional upload/Synchronisation traffic of about 500MB - not good.
Therefore, I thought I could just copy the Masters folder from within the photolibrary to OneDrive (the files in there are not altered so often-hence less traffic) and just create a symlink inside the photolibrary that points to the Masters folder on OneDrive. This way all the high traffic files would remain local, backed up by TimeMachine, and only the actual data repository would be in the cloud.
I tested this with a test library, and in Finder this even works just fine, however, when I start the Photos app it tells me the library is protected and/or access rights / file permissions are corrupt and need repair - but this does not help. Funnily, when I just rename the Masters folder inside the photolibrary (inside the package) and then let the symlink point to that renamed folder, it works.
Can anybody explain this behaviour or has a hint how to fix this? Is there a reason that symlinks inside packages pointing to folders outside the package don't work? Or is this a Photos specific thing? Or do I just make a mistake or do I need to adjust the file permissions/attributes?
I tried all sorts of things/combinations, but without success - therefore, your help, expertise and guidance would be much appreciated - thanks!