How do I restore a Photos Library using iCloud on a MacBook?

Why don't you restart your old Mac in "target mode" and use it to initiate your new Mac. It works exactly like initiating your new Mac from the most recent Time Machine backup of your old Mac. It'll copy your entire Photo Library and should transfer all the data (including people etc.) to your new Mac. I didn't upgrade to a new Mac since I started to use the iCloud Photo library but I know that once you restart your new Mac (after the long initiating process) you need to log into your iCloud account and just continue from there.

Why don't you restart your old Mac in "target mode" and use it to initiate your new Mac

This will work well for everything but an iCloud Photo Library.

When you sign again into iCloud, the library you copied to your Mac will be treated as a new library, and you cannot enable iCloud Photo Library again on the new Mac, unless you have signed up for enough iCloud storage to hold the Photos Library twice - the version already in iCloud and the copied version. Photos will upload the copied library to iCloud in addition to the version already in iCloud and merge it into the existing library. For example, my library needs close to 200GB. I had to increase the storage plan to 1TB, just to be able to make the copy on the new Mac sync with iCloud. By downloading into an empty library I avoided the painfully slow upload for photos that are already in iCloud (it took ten days on a fast Wi-Fi the last time I tried) and I could have saved the money for the more expensive storage plan, that I rarely use.

I now use iCloud to back up my entire photo library (over 200gb). How do I restore a Photos Library (including all Photos data like faces, events, etc.) on my MacBook Pro when my MacBook Pro needs to be replaced?

You can create a new, empty Photos Library on your new Mac, and then enable iCloud Photo Library for this new Photos Library. The library will download from iCloud, and most items will be restored.

But iCloud is not a backup. It is a central storage to keep all libraries updated across all your devices.

There are some items that will not be restored from iCloud, for example the Faces albums or your projects.

This document describes how a library will download from iCloud to a different Mac:

Use Photos and iCloud Photo Library on multiple Mac computers - Apple Support

After you sign in, these items appear in the Photos app on all of your Macs:

• All original photos and videos
• All folders and albums
• Smart Albums
• Keywords
• Searchable keywords based on Faces tiles
• Key photo selections

These items are available only on the Mac where you created them:

• Books, cards, and calendars
• Slideshows
• Keyword shortcuts
• Unused keywords
• Last imported album (this album contains photos you most recently imported on a specific Mac)
• Faces tiles and Faces data

I would not rely entirely on iCloud as a backup for your photos, but occasionally create a copy of your Photos library on an external drive. This way you can restore your library, even if you should have problems with the internet connection, and it will be faster.

Yes and no.

Whenever you restore a library from a backup, or simply open a copy of a library on an external drive and use it as your current iCloud Photo Library, Photos will upload all photos to iCloud and compare them to the image files that are already there. Photos will not create duplicates in iCloud, but this upload to compare the photos can take a long time. It will always happen, when you switch between iCloud Photo Libraries or even, when you repair a Photos Library.

You're welcome 🙂