Danger of file loss with Photos app.

[psydii]

Edit: actually depending on how they do it deleting an old library may still leave the files in the disk... But still worth knowing that both library's can co-exist without taking up twice the space.

 

Slightly wrong but:

This is pretty important if you know people whole are technical enough to know how to delete stuff, and gung-ho enough not to research things properly before committing an undoable act:

:end of slightly wrong bit.

 

https://support.apple.com/en-us/HT204476

 

Photos saves disk space by sharing images with your iPhoto or Aperture libraries

Learn how Photos stores images when you migrate your iPhoto or Aperture library and saves disk space by sharing images.

 

When you migrate a photo library from iPhoto or Aperture, the Photos app creates a new library structure but doesn't duplicate your images. Instead, Photos saves disk space by creating links to the original and preview versions of your images.

When Finder reports the file size of your Photos library, it includes all your originals and previews. It may look like your remaining iPhoto or Aperture library is taking up twice the space on your hard drive, but it isn't—your images exist only in one location, even though you may have more than one photo library.

After you migrate your iPhoto or Aperture library to Photos, you might feel tempted to delete your original iPhoto or Aperture library. Because the migrated library takes little additional space, you don't need to delete the original library.

You can still use your original photo library with iPhoto 9.6.1 and Aperture 3.6 after you've migrated it to Photos. Any changes you make in iPhoto or Aperture after you migrate to Photos, like image edits or album changes, will be visible only in iPhoto or Aperture.

Last Modified: Apr 8, 2015

 

Hope this helps stop at least a few people making a n avoidable mistake!

Edited April 9, 2015 by psydii
Probably factually incorrect subject line.