Attachment on disk

Hi

I’m using rt-externalize-attachments and everything work fine. I just like to known, is they are anyway to find the actual file on the filesystem ? It’s like the file are put in a tree with some md5sum_thing. But if I got a ticket with attachment is they are anyway (even through the database) to find the actual file on filesystem.
Other question : when someone use a huge picture as signature and we got multiple exchanges how many time this picture are store on the files sytem ?

Regards