iPhoto to Photos from external hard drive

To pen your iPhoto Library with Photos, as Terence Devlin said, drag the iPhoto Library onto the Photos icon. Photos will create a new library from it. The file system format of the external drive needs to be MacOS Extended (Journaled) and the drive needs to locally mounted, not a network share.

After the migration you will see two libraries - an iPhoto Library.migratedphotolibrary and a Photos Library.photoslibrary . You will still be able to open your old iPhoto Library.migratedphotolibrary in iPhoto, if you need to check the old library. Keep iPhoto installed, and keep the old library, until you are sure, that there are no issues with your new Photos Library.

How Photos handles content and metadata from iPhoto and Aperture - Apple Support

Select the drive in the finder and get info - the format is part of the info window

for details on the format see this - Where is it safe to store a Photos Library? Requirements for the external drive

as to TimeMachine by default it does not backup external drives - you can change this in the TM preferences - but be aware that Apple has warned that restoring a Photos library stored on an external drive from a TimeMachine backup not work due to permissions issues so it o=would be good to have another backup for your Photos Library

LN

Will this take up memory on my Mac? Previously in iPhoto, it would automatically just open from the external hard drive, but now that I've upgraded and have Photos, I am getting an error when trying to link it directly to the external hard drive. I have tons of photos and don't want them taking up my computer's memory. TIA

I am getting an error when trying to link it directly to the external hard drive.

What is the error message? And what is the file system format of your external drive?

A library used with Photos needs to be on a drive formatted MacOS Extended (Journaled) and not used by Time Machine, and locally mounted, not a NAS:

The error said something about permissions and I found something giving me the solution, but now I'm getting the error that I don't have enough disk space, which leads me to believe it's trying to import all my photos from my external hard drive onto the computer. I don't want this.

How can I find out if the drive is formatted MacOS Extended? I can tell you it's a Seagate Backup Plus Drive that plugs in through USB. I assume I have Time Machine doing the back up - I set it up quite some time ago.

I'm hoping to keep the same setup I had on iPhoto, where it opens up from the external hard drive. As mentioned earlier, I just don't have enough space on my computer for all my photos. Any suggestions?

The error said something about permissions and I found something giving me the solution, but now I'm getting the error that I don't have enough disk space, which leads me to believe it's trying to import all my photos from my external hard drive onto the computer. I don't want this.

When you open an iPhoto Library in Photos, the Photos.app will create a new Photos Library from it. And by default, it will create the library in the same folder, on the same drive as the original iPhoto Library is. But it can only do that, if the drive is compatible with Photos. If the file system format is not MacOS Extended (Journaled), Photos will create the new library on your system drive instead, and you will run out of storage. The same will happen, if the drive is used as a Time Machine drive. So, check the file system, and if it is wrong, move you iPhoto library to a correctly formatted drive for the migration.

Only one way to do it - open the Library with the new app. That's it.