Advice on mirroring Apple Photos library between 2 external HDDs and symlink/hardlinks

[EkoThree]

Hi,

Ran some searches on this forum and Google, but had trouble finding information.

For your background, I'm on a Mac using the latest version of Sierra.

I recently discovered FFS and would like to use it to mirror data from a 1TB external HDD to a new 4TB external HDD.

The old HDD primarily contains the default Apple Photos library. (~500GB, 60k images).

My question for the FFS community is about symlinks and hard links as it pertains to Apple Photos. I have a very basic understanding of symlinks and don't know much about hard links.

From everything I've read about the latest version of Photos is that it converts the old iPhoto library and heavily relies on hard links. It is also my understanding that there is quite a bit of symlinks used amongst assets in Photos/iPhotos as well. As a matter of fact, running the below bash command for symlinks returns quite a long list:

ls -lR 1TB-External/ | grep ^1


So here is my question for this here that are Mac familiar: what settings do you advise using in FFS to successfully move a copy of the Photos Library from one drive to the other without breaking all the various links?

Once the sync is complete, I'd like to point Photos to the new copy of the library to use as my system default.

Thanks.