Photo storage / sort

Photo storage / sort

I'm wondering what the best practice is for photo storage. I'm in the
business of storing photos with a user. Each user can have up to 35 photos
and we currently have around a 100k users. I currently reference the
photo's from a database.
My proposed solution is a hash of the photo name like so.
f56c0de1c61fdb926e79e8a0a65bd12930c9.jpg
broke out into directories like so
Photo 1
f5/6c/0d/e1c61fdb926e79e8a0a65bd12930c9.jpg
f5/6c/0d/e1c61fdb926e79e8a0a65bd12930c9_thumb.jpg
Photo2
ec/1c/55/bfb660548a6770238668c4b117d92f.jpg
ec/1c/55/bfb660548a6770238668c4b117d92f_thumb.jpg
database Stored in the database as a comma separated array like so for
sort ordering.
ec1c55bfb660548a6770238668c4b117d92f,ec1c55bfb660548a6770238668c4b117d92f
Is this the most efficient way to do this? and is it scalable? I'm not
sure if the photo hash is to large and I'm also not sure if the directory
size is correct.
I created a more detailed post over on stackoverflow, just not sure where
this question belongs.
http://stackoverflow.com/questions/19106596/how-to-store-photo-on-file-system-and-store-sort-order-in-database