Using a backup version of System Photos Library. Will iCloud recognize it when I set is as my new System Photos Library?

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Using a backup version of System Photos Library. Will iCloud recognize it when I set is as my new System Photos Library?

Due to size of my System Photos library, I keep it on an external drive.

It became corrupted, with unrepairable permissions, so I am now using a backup of the System Photos library, which has been copied to a RAID which will be my new location for the library.

When I switch on "make this my System Photos Library" in Photos > Settings > general, I get the warning iCloud will be switched off, all photos not downloaded will be removed from my mac.

Does not make a lot of sense, how can photos that are not downloaded be removed from a Mac, if they have not been downloaded to it?

But my principle question is, when I switch to a new System Photo Library, which is identical to my original System Photo library (except for a most recent addition of photos from my phone), will it recognize it as the same contents to what is currently in iCloud? or will the original library in iCloud disappear, and the new one be entirely uploaded? (mine is 600GB, so I would like to avoid that)

Since any drive hosting a System Photo Library can fail, I imagine that iCloud could recognize a user assigning a backup. However it is not obvious it can.

Any insights greatly appreciated.

MacBook Pro 15″, macOS 14.3

Posted on Mar 6, 2024 11:02 PM

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Answer 1

Top-ranking reply

marten berkman Author

Level 1

93 points

Mar 8, 2024 10:24 AM in response to léonie

Hi Léonie! Thanks for your input again.

So I turned on "System Photos Library" for the new (backup) library and location, and it seems to have gone seamlessly. iCloud never turned off, or if it did, it turned back on again before I checked its status. The iCloud Photos library seems to have checked its contents against the new library, and recognized it, because it proceeded to sync only the photos I had added to my new System Photos Library (I actually added the photos before turning on System Photo Library setting), ie it recognized the whole data base of original images and did not remove or duplicate anything there.

So, all is good with turning a backup (I use Carbon Copy Cloner) of a System Photos Library, into the new System Photos Library, even if photos have been added to the new library in the meantime.

I appreciate it when the software/OS can handle such large data bases smoothly.

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Answer 2

léonie

Level 10

203,429 points

Mar 7, 2024 1:37 AM in response to marten berkman

You are getting this message "... iCloud will be switched off, all photos not downloaded will be removed from my Mac" because only the System Photos Library can sync with iCloud Photos. This is why your current library can no longer sync with iCloud Photos, when you make the new library your system Photos Library and Photos will remove all incomplete images from the previous system library, the thumbnails and optimized versions, where the original image files have not been downloaded, but replaced by smaller, optimized versions. If you have not used "Optimize Mac Storage" with iCloud Photos, there may not be any incomplete versions , that will need removing.

Once you make your restored library your System Photos Library you also enable iCloud Photos for it and Photos will merge it into your current iCloud Photos Library then download any missing items from iCloud. The new upload of the restored library may take several days for a very large library.

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Answer 3

Mar 7, 2024 12:53 AM in response to marten berkman

> RAID which will be my new location for the library

Make sure that the Photos library is on APFS or MacOS Extended -formatted volume.

Other formats like exFAT, NTFS etc are not supported, and if they initially seem to work, they might corrupt the library later.

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Answer 4

Mar 8, 2024 10:15 AM in response to Matti Haveri

Thank you Matti! Yes, I have these disks formatted MacOS Extended.

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Using a backup version of System Photos Library. Will iCloud recognize it when I set is as my new System Photos Library?

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