Blogs.dir scalability

Hello,

How to host the user uploads on a large wordpress multisite ? Like Multi-db for databse, I am trying to figure out the best way to improove scalability of the storage.

I tought about Amazon S3 services, move blogs.dir to another container, but still have a problem at 5'000Gb. So what do you guys recommend?

Thankyou for your help.
Cheers.
Luis