Directory structure after upgrade to iPhoto 6

Question

After upgrading to iPhoto 6, it appears that my photos were copied from the old, date-based structure into a new directory structure, but the old structure was left behind.
What is the layout of the new structure, and can the remaining old structure be discarded at this point?
Thanks for any insight you might be able to offer...

Answer 1

The new structure organizes photos into Originals and Modified folders. There is a third folder called Data that contains thumbnails created for the photos (smaller pictures used for better performance). These three are essential for iPhoto 6 to work.
Each folder contains a folder for each year (a year folder is created if you have even one photo from that year, e.g. a photo from 4/3/2004 will create a folder called "2004" and any other photos from that year will then be placed within it.
Every import creates a serially numbered Roll folder within the year folder. So if you import photos including IMG_234.jpg from 4/3/2004, for example, the location of IMG_234.jpg will be:
iPhoto Library/Originals/2004/Roll 1/IMG_234.jpg
And Roll 1 will have other photos imported in the same session. If you modify the photo within iPhoto (enhance, retouch, etc), the modified copy will exist in:
iPhoto Library/Modified/2004/Roll 1/IMG_234.jpg
The Data folder will contain a thumbnail for the image in the same path as the Originals:
iPhoto Library/Data/2004/Roll 1/IMG_234.jpg
So inside the iPhoto Library folder, you will see some files and those three folders with their sub-structure folders. Other things within the top level of the iPhoto Library folder, are leftovers from the previous structure - such as a folder called "2004" or "2005" that ISN'T inside Originals, Data, or Modified folders.
PhillyPhan's advice is sage. Don't mess with the insides of the iPhoto Library. However, I did verify on my own system after I upgraded, that year folders at the top level of the iPhoto Library are from previous versions of iPhoto. So you could move those, and those only, to a separate folder on your HD. I moved those off to a DVD-ROM and haven't seen problems since.
Remember: Don't touch any files, and don't touch anything within Data, Originals, and Modified folders.