Can i store and access iphotos library on external hard drive (and still have it backup to my cloud network)?

I have two questions regarding Apple photos library.

• Can I store my large Photos library on an external HDD?
• Is it possible to set this HDD to backup via my computer to the same local network attached storage that my computer backs up too?

Notes: I am using a 2015 MacBook Pro running Big Sur, I am backing up to a NAS drive using time machine

This is one of those "fun" non-discoverable Apple settings that you would only know if you knew about this setting already. Yah catch-22. Anyway.

1. Copy the photoslibrary file to the drive you want to store it on.
2. While holding the Option key, launch the Photos.app

Instead of Photos.app opening, you will get something like this

3. Click on the Other Library button and point it to the photos library you just copied to your external drive.

It will open that file and set it as the default, so that the next time you open photos.app it will open that file again. You can verify that by renaming or moving the one in the old default location and launching photos.app normally.

Yes, you can transfer the photo library to an external drive or NAS and still back it up.

You can simply copy and paste your current library (usually the .photoslibrary package is located in /user/Photos/) to your external storage device. Make sure to not interrupt the copy process, because restarting the copy process means you will lose all progress (unless you use e.g. rsync).

To make sure which photoslibrary you are opening follow Steves answer.

Backing up the library also still works e.g. with TimeMachine. Just go into settings -> TimeMachine -> options -> select the external device -> hit the - sign. This will backup the whole external device, but you can exclude all other files by hitting the + sign in that same view and selecting everything except the photoslibrary.

You didn't ask how many drives are needed for Time Machine but the answer is more than one. Set up multiple drives in rotation and keep one off site if you can. Having one connected regularly is awesome, but more destinations will save your photos if disaster strikes.