Should I split Photos library to create space on system drive?

A second question is: is there a way to sort my photos by file size to see which are the largest files? This was easy on Aperture but I can't figure it out in Photos.

Photos cannot sort by file size, but I am using PowerPhotos to browse my Photos library in list view. Even the free trial version of PowerPhotos can show you your Photos Library with more metadata displayed than Photos can. In list view, you can click the column with the file size and sort the currently selected albums by the file size. PowerPhotos takes a long time to open the library however. So I keep it simply open allay.

My question is: should I just work on trying to delete photos and videos I know I will no longer use and reduce the size of my System Photo Library that way (time consuming), or should I create a new library on the 6TB external drive and move my videos there?

If you are continually carrying your MacBook Pro around, it is no joy to have always an external drive connected. My work-around has been, to keep the library on the internal drive small - I rigorously delete photos and videos, from the library, that are not my favorites that I always want to be accessible. Now the library o. the internal drive has all photos and videos that are important to me. On my external drives are backup copies of the originals and aa larger archive library with all photos.

Phots has no support to split libraries, like Aperture had. We cannot export partial libraries. That is why I copied the complete library as an archive to the external drive (and to the backup drive of the external drive) and then started to weed out the remaining library on the internal drive. Knowing that the original library is still there on the external drive, it is easier to decide which photos to keep and to delete.

Alternately you could enable iCloud Photo Library for the library on your internal drive, with "Optimize storage". The original image files will be stored in iCloud, and if the Mac needs to free storage, iCloud Photo Library will remove older originals and keep only the thumbnails stored locally. This would not work for me, because it makes it difficult to keep a local backup with many of the photos only in iCloud. And I want my photos on my MacBook Pro always accessible when traveling, without internet connection.

your decision is your decision - I personally us iCloud Photo Library with optimized photos to reduce library size

referenced photos are not a good idea

For moving photos to a second library and for sorting by size PowerPhotosis the solution

LN

For moving photos to a second library and for sorting by size PowerPhotosis the solution

It is only second best solution, Larry, IMHO. You will get the same result with PowerPhotos as with "File > Export", only a bit easier. But even PowerPhotos cannot move the edited versions paired with the originals as a Master-Version pair to the new library; you will have to move the photos twice, once to move the edited versions and once to move the originals. It will no longer be possible to revert the edited versions to the original, or to undo edits separately. ans it will not move the projects either. The only completely lossless way to create a partial library is to duplicate the library, then to delete all items from the v´copy that we do not need. This will keep the original masters and the edited versions paired ans will save the projects as well.

I'm sure, the PowerPhotos team would love to offer a better solution, but the Photos interface does not allow it. See: https://www.fatcatsoftware.com/powerphotos/Help/copying%20limitations.html

Copying limitations

Due to various technical limitations on what’s possible with the Photos app, there are some types of items and pieces of information that cannot be copied between libraries by PowerPhotos. Below is a summary of what can and cannot be copied, and some caveats that apply to certain types of items.

Fully supported: photos and movies, keeping keywords, descriptions, titles, dates and favorites intact; albums, folders, and moments.

Partially supported: locations, smart albums, original vs. edited version of a photo, bursts, live photos.

Not supported: reversable photo edits, manually assigned locations, faces, and projects.

See the link above for more limitations - live photos will not survive the transit, for example.

since OP stated

and move 2000 videos there

Moving the originals of videos will lose nothing for videos (either using PowerPhotos or export/import) and since PowerPhotos is the only know current solution to sorting by size and the easiest solution for doing exactly what the OP wants to do it is my recommendation

LN

1) If you determine you need a photo or photos from the full library backup on the external drive that you already deleted from your laptop file, do you work with them directly in the backup library? Or do you export them and import them back to the laptop system file, as you now want to keep them? I understand that edited and original files would be separated this way.

I rarely need to look at the archive, on ly when I detect corrupted image files in my library and need to restore the original image file. Then I reimport the image to my main library on my Mac Book Pro and copy and paste the adjustments and metadata from the edited version in my main library.

2) I fully understand what to do with photos up to this point, but what do you do on an ongoing basis? Do you simply keep your system file as pared down as possible going forward, with only your favorite photos and videos? Or do you occasionally back up the whole thing again to a third library on the external drive and then delete from the system file? I can see that you can't back up again to the first external drive library or you will lose the original photos from the past that you deleted from the system file.

When I import new photos to my current working library, I import them to the archive library as well, before I start editing. I only edit the keepers in my smaller library.

Once a year I copy the current smaller library to the archive drive as well.

You're welcome 🙂 Good Luck!