how are files stored on disk?

[Chuck Remes]

I've been reading a bit about mogilefs lately and have a couple of  
questions I'm hoping the current users can answer.

1. How are files stored on disk and in what directory structure? Do  
they have meaningful names or do they use a unique hash as their name?

2. Related to 1, if all files are stored in one (or very few)  
directory(ies), how does the node's file system performance scale?  
I'm interested because I realize many filesystems have trouble with  
directories containing thousands or tens of thousands of files. In  
practice is this a problem afflicting anyone?

3. The list archives indicate there are problems with moving files  
larger than 50MB or so. I have an application where some files are  
several hundred MB or even in the low gigabytes. Is this a limitation  
of perlbal or some other mechanism? Would it be hard to swap the HTTP  
PUT mechanism with rsync or another tool better suited for large files?

Thanks for your help.

cr