distributed file system that works well with multiple small files

Hi my use case is quite specific. I have 20 Windows 7 machines constantly creating files in my storage; around 98% of these files are 2.1 MB. On average we create 24 million files every 3 days, and this number may increase in the near future as we may need to add new clients to our system. I do not modify files (just create, read, copy and delete). I have seen Reiser4, which looks promising, but I also would like to have the capability to replicate the files across multiple storage nodes across the network, so I can have a fault tolerance system in place. Any suggestion?