I’ve got over 100GiB of photos (JPEG and RAW) taken over the years, and they don’t comfortably fit on a laptop. The laptop is also shared by everyone in my family, each with their own account, so what to do?

I found out that if you hold down the option key when you start iPhoto it asks for the location of your iPhoto Library — so that takes care of the first problem — just plug in a big external hard drive and you’re set.

There’s one glitch to having the photos on an external drive, though — Time Machine ignores exernal drives by default. Go into System Preferences… > Time Machine. Click “Options”. You’ll see your external drive in the “Do not back up:” list. Click the external drive holding your photos, then click the minus button.

The next problem is how to share the library with others. That’s described quite well by a Mac OS X Hint. Note that the following assumes you’ve named your external hard drive “Photos”.

Step 1: Enable ACLs:

sudo fsaclctl -p /Volumes/Photos -e

Step 2: Add the people that can use iPhoto. Replace “USERNAME” with the short login name of the people that you want to be able to use iPhoto:

sudo chmod +a "USERNAME allow read,write,delete,list,search,add_file,add_subdirectory,delete_child,file_inherit,directory_inherit" \
  /Volumes/Photos/iPhoto\ Library

Creating a group account, subscribing the users to that group, and letting group have read/write/execute to the directory should work, but the umask may not be 775. It’s something to check if this doesn’t keep working.