How to sync selected photo albums between your Mac and your iPhone. ($29,95 — no affiliation) which allows to seamlessly copy albums between different Photos libraries. How to Combine Multiple Photos Libraries Into a Single Library Saturday, July 1st, 2017 Author: Tom Nelson. If you’ve been working with the Mac’s Photos app (or even the older iPhoto or Aperture apps) for any length of time, there’s a good chance you have multiple image libraries. Switching libraries. With multiple libraries on your Mac, you can switch between them very easily using two methods. The first is using the same library manager, so simply quit and relaunch Photos with the Option key held, and you can then select your library. Because Photos for OS X replaces both of Apple's existing photo apps, Aperture and iPhoto, you're going to need to migrate your Aperture and iPhoto libraries into the new Photos app if you want to.
- Using Different Photos Libraries Mac Os
- Using Different Phots Libraries Machines
- Using Different Phots Libraries Machine
- Using Different Phots Libraries Macbook Pro
- Using Different Phots Libraries Mac Os
Photos User Guide
When you import photos and videos into Photos, they’re copied to the Photos library in the Pictures folder. If you prefer, you can store photos and videos outside the Photos library (for example, in a folder on your Mac or on an external drive) and still view them in Photos. Files stored outside your library are called referenced files.
Referenced files aren’t automatically uploaded and stored in iCloud, and they aren’t backed up along with the rest of your files when you back up your photo library—you must back them up manually. To avoid manually backing up referenced files, you can move or consolidate the files into your library.
Store imported files outside the Photos library
In the Photos app on your Mac, choose Photos > Preferences, then click General.
Deselect the “Copy items to the Photos library” checkbox.
Now, when you import photos or video, Photos leaves the files in their original location and accesses them as referenced files.
Find a referenced file in the Finder
In the Photos app on your Mac, select a referenced file.
Choose File > Show Referenced File in Finder.
Copy referenced files into a Photos library
You can copy referenced files into your photo library so they’re easier to back up and are automatically stored in iCloud if iCloud Photos is turned on.
In the Photos app on your Mac, select the files that you want to copy into the photo library.
Choose File > Consolidate.
Click Copy.
Copying photos from one Mac to another
If you want to copy photos from a library on one Mac to a different library on another Mac, you can do that with two basic steps. First, follow the instructions in Accessing an iPhoto library on another Mac so that one of your Macs has access to both libraries. Then, you can perform any copying between those libraries just like any other libraries on your Mac, including copying albums, events, or photos, or merging libraries.
This folder can run quite large just because so many apps cache something in there. If the cache /Library/Caches folder is over 3Gb then you have something that is caching quite a lot. On the three machines I just checked none had a /Library/Caches folder over. Deleting the System and Users Cache: System Cache is present in the Library folder. In some devices, Library folder is hidden by default. You can find it by going to Go in the menu bar and pressing down the Option key on the keyboard. The procedure mentioned below is required to be followed to delete system cache: 1. Deleting library cache mac.
When copying between Macs, here are a couple things to watch out for:
iPhoto library open on the other Mac
How to delete iPhoto library on your Mac. Click on the iPhoto Library listing, and without letting go of your mouse or trackpad button, drag it until it’s over top the Trash icon on your. You can select (click on) the iPhoto Library, then right-click on your mouse. 
Using Different Photos Libraries Mac Os
An iPhoto library can only be open by one copy of iPhoto at a time, so if iPhoto is still running on the remote Mac when you try copying photos, you will probably receive an error message from iPhoto when you try to open that library, complaining that the library is locked. If this happens, make sure to quit iPhoto on the other Mac before proceeding with copying your photos.
Different versions of iPhoto installed on the two Macs
Using Different Phots Libraries Machines
Ideally, both machines should be running the same version of iPhoto. iPhoto Library Manager will allow you to copy between libraries of different versions, but the library that you're copying to must always match the version of iPhoto that's installed on the Mac you're using iPhoto Library Manager on.
Using Different Phots Libraries Machine
Using Different Phots Libraries Macbook Pro
If the destination library is newer than your version of iPhoto, you won't be able to perform the copy, and you might want to consider working on the Mac with the newer version to perform your copying.
Using Different Phots Libraries Mac Os
If the destination library is older than your version of iPhoto, then iPhoto will prompt you and ask if you want to upgrade the library to the new version of iPhoto. If you tell it to upgrade the library, and your other Mac is still running an older version of iPhoto, then you will not be able to access the upgraded library from that other Mac without installing the newer version of iPhoto itself. So, don't upgrade the library unless you're sure you have the right version of iPhoto installed on all the Macs you want to access that library from.