Digital Photo Archive System

1. You need a Photo Manager that can support multiple libraries.
2. You need a library that syncs with the iPhone
3. A second library on the iMac that doesn't sync with the phone
4. A third library on the external HD, that can sync with a Cloud service

Then you also need an extra HD for local back up.

There is no app that can open multiple libraries simultaneously. Or perhaps, better said that there is none I have found.

As you're talking about an Archiving system I do not recommend Photos for the task for a single, simple reason: when you import files into the Library it renames them. While images can then be exported from the Library, and regain the correct filename on export, in the case of disaster recovery, where export is not possible, then you have a real issue. You can mitigate the risk of disaster with multiple back ups, but, for me, renaming the original is a deal breaker. YMMV.

One app that might be worth considering for the task is OnOne Photo Raw. Rater than creating an opaque library this app rather catalogues folders that you choose and doesn't change the files in any way. That means you can have access to all three of your folders (for syncing to phone etc) in the one window at the same time. As the files are stored in the Finder, then a back up to a online service is straightforward. They have recently added a module for syncing to iOS devices.

Here is what I do.

I run two libraries. I pay for 200GB of iCloud, and have a "main" library holding all my recents, that is synced with iCloud and resides on my system drive. All these photos are available on all my devices. Currently I have a year of photographs there, taking up about 1/4 of my iCloud space.

I also have an archive library which holds everything older. It is on a separate drive (correctly formatted and prepared - see link below**). I use powerphotos to periodically copy photos from my main library to my archive library.

I am very very rigorous about backups. The main library is backed up to time machine. In addition both libraries are regularly copied to a second external drive. Finally I periodically export all original images (so that I have the actual image files separtely from the photos library) and copy those to a network drive backup. I have a copy of these stored away from home also (mitigate risk of fire/theft).

Tony (in cold, wet UK :-) )

**The external storage must be formatted APFS or MacOS extended (journaled), and not be (or have been) used for time machine. It must have the 'ignore ownership" checkbox ticked. It should not be on a memory stick, SD or similar. It stands to reason that if you want any sort of reasonable performance it should be a fast drive with a fast connection.

See

https://support.apple.com/en-gb/HT201517

It is also possible with Photos for Mac, but how depends on your system version. Basically, we can have several Photos Libraries, and one dedicated library as the system Photos Library, visible in the Media Browser and synching with iCloud. See: https://support.apple.com/guide/photos/create-additional-libraries-pht6d60b524/mac

Which system version are you using on your iMac? And is the system version given below your question still valid - iOS 10?

The unfortunate new feature, that we can no longer recover our photos with the original filenames from a Photos Library, if we cannot use Photos to open the library, started with macOS 10.15 Catalina. In earlier versions of Photos we still can recover the originals relatively easy.

But if you are already running Catalina or Big Sur, you can still archive your original photos by exporting them to folders.

For me, this is working:

• I am using a small Photos Library in the pictures folder of my Macs, only with the photos I want to sync with iCloud Photos to all my devices ( my favorite photos and the recently imported photos, I am currently working with). I'm keeping the library small enough to keep it completely on the Mac and my other devices, without having to use "Optimise Storage". This way, it is easier make backups.
• All other photos are archived in separate photo libraries on external volume, and this volume is regularly cloned with Carbon Copy Cloner to a second external volume as a backup.
• I am using PowerPhotos to manage the archive Libraries and to move new photos from my iCloud Library to the arvchive library. PowerPhotos can only move photos that are mirrored locally - best with "Optimise Mac Storage" disabled.
• To save the originals I am regularly exporting new photos to a set of folders on my Media drive. I am using the folder naming preset "Moment Name". This way the exported photos will be saved in folders named by the location and the date and are easy to find.