Elgg 1.8 and 1.9 data directory map. Where?

Hello,

I try understand how 1.8 data directory map 1.9 data directory.

I know 1.8: Register year -> Register month ->Register day->Something (GUID?)->elgg area?->data files

How this is in 1.9?

I check learn.elgg.org I cannot find. I miss?

Thank