It seems the official way to backup your Photos Library is to literally drag it from your OSX desktop onto your external storage. So I did that.

Now, I want to know how to do a diff between the new Photos Library created on external disk and the original Photos Library on the OSX, before I delete it from my OSX forever.

How to do this using official Apple methods/utils or Linux CLI?

1 Answer 1


One note of caution, dragging photos to the desktop does a lossy export and you’ll lose all sorts of metadata and photo quality if you bypass the export functionality.

That being said, there is a tool that lets you merge / duplicate / check that two different libraries have the same or different photos (as well as the super useful deduplication features for which I pay gladly alone for this software).

There is a demo version you can try - so if there’s not another method, you can do far worse than starting with this app. It’s fast, reliable, updated and supported by the author and been around for quite many years.

  • 1
    Thank you ! Upvoted btw, but it won't show up until my rep increases to > 15 =)
    – pqpqpq
    Commented Mar 25, 2019 at 2:09
  • Thanks for the metadata warning! It's interesting that my quick google for how to back up the photos library had found an apple support page instructing us to just drag it to back up .... -.-""
    – pqpqpq
    Commented Mar 25, 2019 at 2:10
  • 1
    Also - I meant I was dragging the single icon "Photos Library", not individual photos.. does it still lose metadata that way?? I wouldn't think so??
    – pqpqpq
    Commented Mar 25, 2019 at 2:12
  • Dragging the entire library - that's just fine @ppp . Sorry I didn't understand what the backup operation entailed. I've seen what I described more times than I can shake a stick at.
    – bmike
    Commented Mar 25, 2019 at 11:02

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