I have an iPhoto library that's taking up about 65 GB. Because of that I can't update my MacBook Air. When I try to open the file call "iPhoto Library" I get a message saying it's been converted to a Photos library. So what would happen if I delete the iPhotos document? Do those iPhotos pictures get deleted from Photos? Or are they duplicates now? How do I even know what they are and if they're viewable?
MacBook Air 13″, macOS 10.15
I would move the iPhoto Library to an external volume, where you can archive it, just in case, if you do not have already a copy of the Photos Library archived somewhere? Occasionally I need my old iPhoto and Aperture Libraries to recover original photos, if one of the originals got corrupted. Unfortunately we may be noticing too late, years later, if a file got corrupted, only after it has been gone from the Time Machine backups as well. The problem is, that our Photos Libraries are mostly only showing us the previews and thumbnails, and all may look well, until we try to edit a photo and discover the corruption. To be able to fix this, we need separate copies of the original image files. I just had to go back to an early iPhoto Library from 2002, to recover the original version of a damaged JPEG. My Time Machine backups were only holding the damaged version.
Corrupted Originals, the Insidious Danger - How to Protect our Photo Libraries - Apple Community
If you want to open the iPhoto Library again in Photos you just have to replace the filename extension by renaming the library in the Finder. Photos changes the filename extension from "iPhoto Library.photolibrary" to "iPhoto Library.migratedphotolibrary". The changed extension is telling Photos that you already created a Photos Library from this iPhoto Library. After changing ":migratedphotolibrary" back to ".photolibrary", Photos will open it again and create a new Photos Library from it.
I would move the iPhoto Library to an external volume, where you can archive it, just in case, if you do not have already a copy of the Photos Library archived somewhere? Occasionally I need my old iPhoto and Aperture Libraries to recover original photos, if one of the originals got corrupted. Unfortunately we may be noticing too late, years later, if a file got corrupted, only after it has been gone from the Time Machine backups as well. The problem is, that our Photos Libraries are mostly only showing us the previews and thumbnails, and all may look well, until we try to edit a photo and discover the corruption. To be able to fix this, we need separate copies of the original image files. I just had to go back to an early iPhoto Library from 2002, to recover the original version of a damaged JPEG. My Time Machine backups were only holding the damaged version.
Corrupted Originals, the Insidious Danger - How to Protect our Photo Libraries - Apple Community
If you want to open the iPhoto Library again in Photos you just have to replace the filename extension by renaming the library in the Finder. Photos changes the filename extension from "iPhoto Library.photolibrary" to "iPhoto Library.migratedphotolibrary". The changed extension is telling Photos that you already created a Photos Library from this iPhoto Library. After changing ":migratedphotolibrary" back to ".photolibrary", Photos will open it again and create a new Photos Library from it.
The exact same files for the photos are used for both and the individual photos aren’t duplicated, so deleting the iPhotos library—which is possible, and won’t disrupt Photos—won’t appreciably reduce your storage usage.
Notes on Migrating an iPhoto Library from iPhoto to Photos for Mac - Apple Community
https://apple.stackexchange.com/questions/180979/importing-an-iphoto-library-in-photos/282371#282371
But being professionally cautious, I’d have backups of everything first.
iPhoto Library - Can I delete it?
