Am I able to delete the "migrated photo library" after I convert from iPhoto to Photos?

I deleted it, and got an extra 65GB of storage on my hard drive.

the space saved depends on many things and generally is very little - in a few unusual circumstances it may be more or even a lot - hence the general recommendation (probably over 99% correct) that very little space will be saved - the longer it has been since the migration and the more photos that have been deleted for Photos the greater the saving will be

LN

an old but interesting topic I know but I thought I'd correct a small point in the first article.

When two file's point to the same inode changing one WILL change both files, it must be iPhoto that is duplicating the files. Also finder reports the 'wrong size' (double) it's not clever enough however du -sk Pictures works

eg.

maci7:link simon$ ls -li total 16 24150431 -rw-r--r-- 2 simon wheel 6 20 Oct 15:36 f1 24150431 -rw-r--r-- 2 simon wheel 6 20 Oct 15:36 f2 maci7:link simon$ ls -i 24150431 f1 24150431 f2 maci7:link simon$ cat * file2 file2 maci7:link simon$ echo file1 >f1 maci7:link simon$ cat * file1 file1 maci7:link simon$

No your correction is incorrect - the files are not duplicated -- this article by Apple is correct - Photos saves disk space by sharing images with your iPhoto or Aperture libraries - Apple Support

and since neither iPhoto nor Photos ever change the original file there is no issue or conflict of any sort - at migration there is no additional disk space used for Photo storage - over time photos deleted from one f=program and not deleted from the other will remain so if you are not using either program after several months it may pay to archive and delete its unused library

LN

sorry I meant the second article ! Specifically…

So what happens if you edit one of those files? Something very clever, it turns out: If I open the JPEG image from the migrated iPhoto library in Photoshop, edit it, and save it, that version is indeed altered—but the version in the Photos library is untouched. Basically, modifying that file causes the link between the two versions to break. They’re different, and no longer connected.

This paragraph is technically mis-leading, since as my post shows, writing to a Unix file that has multiple hard links does not in itself create a separate version of that file.

I suppose Photoshop must be re-creating a new file though i.e when 'do you want to overwrite' is prompted before the PSD is saved as .jpg, it breaks the link. I don't think many people would do this though, I'd just save it as a new file.

due to the size of her iPhoto libraries, one is over 200GB!

For each of the iPhoto Libraries you would need to move the Photos Library migrated rom the this iPhoto Library, and keep a backup of the original iPhoto library on an external drive.