Create new libraries
If the Aperture library becomes large, you can create additional, separate library files to hold more photos. You can create additional library files in different locations on your internal hard disk or on different hard disks. You can also rename library files as needed. Thus, you might have multiple library files with different names in the same location, with Aperture set to access the library file you want.
Create a new, empty library file in a new location
Choose File > Switch to Library > Other/New.
In the dialog that appears, click Create New.
In the next dialog, enter a name for the library in the Save As field, choose a location, and click Create.