Testing iPhoto to Photo migration

Yes, the original library will be as-was after migrating, but do not underestimate how long this will take, 310GB is a large library, weeks possibly, days definitely.

If you use 'Optimize Storage' less than 310GB will be required, if you don't then the full amount will be needed.

Just an add on to Csound's explanation:

If that's it case would I then need some 310+GB of free space?

You will need less than the size of your iPhoto Library for the new Photos Library, because Photos is creating the image files in the new library as hard links to the image files in your iPhoto library. So the image files will be shared between the libraries. Both libraries will be showing the same size in the Finder, but the images will be stored as the same entries in the file table.

Thee links are explained here:

• Photos saves disk space by sharing images with your iPhoto or Aperture libraries - Apple Support
• Six Colors: The (hard) link between Photos and iPhoto

In another word will my current iPhoto library be left unaltered, so that I'm able to use it as a source again for the real migration.

Essentially yes. The iPhoto Library will remain the same, but Photos will change the filename extension from .photolibrary to .migratedphotolibrary to mark it as already migrated.

To open the library again in iPhoto change the filename extension back to .photolibrary or double click the library, and when prompted, select to open it in iPhoto.

Thanks for making up for my inadequacies Léonie 🙂

No problem, Csound1. 🙂

I wish Apple would include these details in links from the Photos Help, and not hide them away in KB articles that we have to search for, or we have to find out by experimenting!

There are very many things that Apple fail to explain in ways that are easily accessible.

If you open the migrated library again, the filename extension will revert to .photolibrary.

I just tested once more, and directly after opening two iPhoto Libraries in Photos it looks like this:

If Photo is using the .jpg files already stored by iPhoto, where are the new imported .jpg files stored? That is the images you import AFTER you've migrated to Photo?

The migration creates a Photos Library. Both libraries contain all image files. The hard linjed files in your Photos Library are independent, full size image files. They are just using the same disk blocks as the originals. You can delete either the Photos Library or the iPhoto Library and the other library will keep working.

Any new file you import to Photos will be stored in the Photos Library, and only be available in Photos. Any new file you import to iPhoto will only be available in iPhoto.