Photos Libraries on more than one device

I have a MacStudio and a MacBook Pro = I thought I had my main Photoslibrary on my Studio but I went on a trip and used my MBP and its Photoslibrary a lot = and it’s listed as the system library on my MBP. And when I went to my Studio I found various photoslibraries but they were topic-limited and I didn’t find the larger general one. Is it possible to have a System photos library on one device separate from the system photos library on another? Or should I have one system photos library on a ‘master’ machine and then what about accessing it on the other?


Thanks.

MacBook Pro 16″, macOS 15.6

Posted on Sep 29, 2025 2:42 PM

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Posted on Sep 30, 2025 11:15 AM

Victoria Herring wrote: … I had the big library on my MBP which was a System Library…I can't find it in iCloud - I did …set it up as a new Master

Some of that is confusing me. For iCloud Photos, there is no Master. All the Photos Library connected to the same Apple Account have exactly the same pictures, and they have exactly the same status. No masters in iCloud!


The System Library is the one used by other apps, like Safari, when you want to load a picture to a web site or you want to use a picture for wallpaper, and so on. And the System Library can be, but isn't necessarily, connected to iCloud. You connect a System Library to iCloud at Photos' Settings>iCloud. If possible, you select Download Originals, since that allows you to be able to back them up, if they're important to you.


When you connect a Library to iCloud Photos, all the pictures currently in the Library are copied to iCloud.com, adding to the pictures already there. Then all those pictures are copied back to that device's Library and to every other connected Library, with Photos doing its best to avoid duplicates. Every connected Library will then have exactly the same pictures.


If you edit a picture on any connected Library, the edits will be copied to all the others. They all will be kept the same, and any operation you do on any device will be copied to all the others. Including mistakes! Deleting a picture on any device deletes if from all devices. That's why we have backups.


The only differences in appearance will be due to the devices' individual limitations. Mobil devices can't show Smart Albums, for instance, but their Libraries have the information.


What do you think?



6 replies
Question marked as Top-ranking reply

Sep 30, 2025 11:15 AM in response to Victoria Herring

Victoria Herring wrote: … I had the big library on my MBP which was a System Library…I can't find it in iCloud - I did …set it up as a new Master

Some of that is confusing me. For iCloud Photos, there is no Master. All the Photos Library connected to the same Apple Account have exactly the same pictures, and they have exactly the same status. No masters in iCloud!


The System Library is the one used by other apps, like Safari, when you want to load a picture to a web site or you want to use a picture for wallpaper, and so on. And the System Library can be, but isn't necessarily, connected to iCloud. You connect a System Library to iCloud at Photos' Settings>iCloud. If possible, you select Download Originals, since that allows you to be able to back them up, if they're important to you.


When you connect a Library to iCloud Photos, all the pictures currently in the Library are copied to iCloud.com, adding to the pictures already there. Then all those pictures are copied back to that device's Library and to every other connected Library, with Photos doing its best to avoid duplicates. Every connected Library will then have exactly the same pictures.


If you edit a picture on any connected Library, the edits will be copied to all the others. They all will be kept the same, and any operation you do on any device will be copied to all the others. Including mistakes! Deleting a picture on any device deletes if from all devices. That's why we have backups.


The only differences in appearance will be due to the devices' individual limitations. Mobil devices can't show Smart Albums, for instance, but their Libraries have the information.


What do you think?



Sep 30, 2025 10:08 AM in response to Victoria Herring

Following up to what markwmsn said,


Two System Libraries on two separate machines, connected to the same Apple account, will have exactly the same pictures, and they will be exactly the same picture as the account at iCloud.com.


A Mac user may have multiple Libraries, but only one is the System Library, and only the System Library can connect to iCloud. Mobile devices have only one Library.


If you see two Libraries with different pictures, then they are not connected to the same Apple Account.


How many accounts do you have?

What do you see at iCloud.com?

Sep 30, 2025 10:37 AM in response to Richard.Taylor

That was part of the problem = I had the big library on my MBP which was a System Library = and I couldn't find it on the Studio AND I can't find it in iCloud - I did copy over the MBP library to the Studio yesterday and set it up as a new Master and also had it used as a System Photo Library = and it is syncing still today [optimized because my Studio has limited space] but I guess that's to be expected.


I have 1 account and plenty of space on my iCloud Drive but when I go in list view I don't find a photo library at all.

Sep 30, 2025 11:40 AM in response to Richard.Taylor

I guess I called it Master so I knew it was the main one -- but your explanation is very helpful. This whole discussion has been helpful. Much appreciated. I did just go into iCloud.com itself [not in list view on my Studio] and the full library is there - all 22K photos....I do need to clean things out but it does help for me to understand better how things are. Again, Many thanks.

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Photos Libraries on more than one device

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